THE FAMILIES OF TRUE FLIES (DIPTERA) OF
R. A. Cannings and G. G. E. Scudder
Copyright © 2006 - All rights reserved.
Extracted from the forthcoming publication The Insect Families of British Columbia.
View the key to the Families of Diptera in British Columbia
Descriptions of Families
Family TANYDERIDAE (Primitive Crane Flies) [Fig. 1]
Considered by some the
most archaic of living Diptera, the Tanyderidae is a family of medium to
large-sized flies with long legs, no ocelli, and dark-patterned wings with a
well-developed anal angle. The 5-branched radius is a hypothetically primitive
condition rarely found in real flies. The antenna has 15 to 25 segments; North
American species usually have 16 antennal segments with the last segment being
shorter than the second last segment. The compound eyes bear erect setae between
Little is known of the
biology of the family. Adults are mostly collected in forests and the larvae are
mostly aquatic. One Australian species bores in the surface of rotten logs
submerged in mountain streams; known larvae of North American species burrow in
the sandy sediments along the margins of streams.
The primitive crane fly
family is a relict group, scattered in the temperate areas of the Northern and
Southern hemispheres – the southern tips of Africa and South America, central
and eastern Asia, Australasia and North America. The family contains 38 species
in 10 genera. There are two genera and four species in North America; the sole
eastern species is Protoplasa fitchii Osten Sacken. The only western
genus is Protanyderus with three species, one of which, P. margarita Alexander, occurs in BC.
Family TIPULIDAE (Crane Flies) [Fig. 2]
Crane flies are normally
slender, very long-legged flies with wingspans ranging from 5 to 85 mm. The
head is variable in shape, often expanded forward into a snout-like rostrum.
The antenna is usually short or moderately long, but sometimes extremely long
in males, reaching four times the body length in some species. The number of
antennal segments range from 5 (some Chionea) to 39 (some exotic species),
but usually there are 13 in the subfamily Tipulinae and 14 to 16 in the subfamily
Limoniinae; antennal segments are sometimes branched in males, but rarely branched
in both sexes (Ctenophora). The eyes are large, usually separated above,
but sometimes joined (Limonia); ocelli are absent. Thorax with distinctive
V-shaped transverse metanotal suture. The long legs are unusually brittly, easily
breaking between the trochanter and femur. The wings are elongate, rather narrow,
reduced or lost in females of some groups, sometimes in both sexes (Chionea).
The venation is normally characterized by two anal veins, 9 to 12 veins reaching
the wing margin, the basal cells extending at least half the length of the wing,
and a distinctive region near the outer third of the wing where the branching
points of Rs, M and CuA often occur together in a transverse line.
Crane flies occur almost
everywhere insects live, from lowland deserts and tropical forests to the high
Arctic islands and high mountain tops. Most live in moist temperate forests,
especially in cool, damp places near water. Larvae develop in fresh water,
especially fast streams, in the intertidal zone, in mosses, decayed wood, wet
leaf litter, organic soils and mud, dry soils, fungi, vertebrate nests and in
the leaves of terrestrial plants. They are herbivorous, saprophagous or
Crane flies comprise the
most speciose family of Diptera – approximately 15,270 species are described. Tipula, with well over 2000 named species and Limonia, with about
200, are among the most speciose genera of Tipulidae. In Canada 593 described
species are arranged in 73 genera. There are 171 described species in 52 genera
record in BC. The province’s most diverse genera are Tipula (35+ species), Dicranomyia (15+ species), Tricyphona (11+ species), Ormonia
(10+), and Nephrotoma (10+). The family includes our largest flies,
at least in wingspan with BC’s largest, Holorusia hespera Arnaud
& Byers, measuring up to 85 mm. This huge rusty-coloured fly ranges from
BC to Arizona and California. Pedicia magnifica Hine was first described
from Vancouver Island; it, and others of the genus, have a striking brown triangular
mark on the wings, which span at least 50 mm. Larvae develop in wet organic
soil along streams and seeps. Males of the orange and black Phoroctenia vittata (Meigen) have feathery antennae; larvae of P. vittata burrow in
decaying hardwood stumps and logs. Population levels of Tipula paludosa Meigen (Marsh Crane Fly), an introduction from Europe, exploded on the south
coast in the 1960s; the root-eating larvae, called leatherjackets, damage lawns
while the adults can be common in houses in September. Throughout BC from late
autumn to early spring adults of several species of wingless crane flies of
the genus Chionea frequently are found striding purposefully over the
snow, especially when the temperature hovers around freezing. Larvae live in
the nests of small mammals. Perhaps the most common and widespread is C.
Family BLEPHARICERIDAE (Net-winged Midges) [Fig. 3]
Net-winged midges are delicate,
slender, long-legged flies, about 3 to 13 mm long. They are usually uniformly
coloured grey or dull yellow-brown. The eyes are large, finely pubescent and
divided into an upper and lower portion; the upper part normally is reddish
in life and is made up of larger facets than the lower part, which is black
in life. Males’ eyes usually meet on top of the head. The three ocelli are borne
on a tubercle. The antennae are short, with 11 to 13, usually barrel-shaped
segments. Most females have slender, serrated rasping mandibles. The wings are
broad with a prominent anal angle; the radius has only three or fewer branches
reaching the wing margin in North American species; M2 is completely
detached basally. There is a net-like pattern of fine folds throughout the wing
membrane, hence the family’s common name.
Distinctive and highly specialized,
net-winged midges are denizens of mountain streams, where the larvae cling to
rocks in rapids and waterfalls, scraping diatoms and other algae, bacteria,
and other organic matter from the rock surfaces. The larvae are well-adapted
to fast-flowing water, having a cephalothorax composed of the fused head, thorax
and first abdominal segment; six ventral suctorial discs attach strongly to
smooth surfaces. The pupae are also attached to rocks, often in the hundreds,
all aligned in the same direction. Wings are fully developed within the pupal
case and adults usually emerge to the water surface in an air bubble. Adults
usually live near streamside rocks or in riparian vegetation and survive only
a week or two. Female adults of many species are predators of soft-bodied insects
such as mayflies, stoneflies and chironomid midges. Feeding habits of males,
and females lacking mandibles, are unknown, but it is thought they might feed
on nectar. Eggs are cemented to streamside rocks although some species oviposit
while entirely submerged in the water.
Net-winged midges are distributed
worldwide; the 300 described species are placed in 27 genera. The family is
usually divided into two subfamilies – the Edwardsininae in the southern hemisphere
and the Blepharicerinae in both northern and southern hemispheres. The relationships
of groups within the latter subfamily are not well understood. There are 27
species in five genera in North America north of Mexico, all in the Tribe Blepharicerini.
BC has four species in two genera: Agathon aylmeri (Garrett) was first
described from the Rockies; A. comstocki (Kellogg) ranges in coastal
mountains south to California; A. markii (Garrett) is recorded from Southeastern
BC, near Cranbrook. Bibiocephala grandis Osten Sacken ranges from the
Yukon south to New Mexico; it is recorded in BC from the Coast range east to
Family DEUTEROPHLEBIIDAE (Mountain Midges) [Fig. 4]
Mountain midges are
delicate flies, approximately 3 mm long, with unusually broad, silvery-blue
wings, and reduced mouthparts. The thorax is dark brown or black, broad and
arched, projecting over the head; the tapered abdomen is pale brown in the male
and dark green in the female. The head is small, transverse and rather
flattened, with the small eyes below the antennae. The eyes lack pubescence and
ocelli are absent. The antennae have only six segments, but the terminal segment
is greatly elongated in males, making the antenna about four times the length of
the body. The wing veins are much reduced however, a fan-like network of
vein-like lines, the result of wing-folding, is striking. The legs are slender;
the empodia of males are flattened, circular discs with long, yellow-knobbed
setae; one tarsal claw is slender, the other is reduced; the empodia of females
are linear and shorter than the two stout claws.
Mountain midges live along
rapidly running streams where the larvae cling (with seven pairs of
finely-clawed abdominal prolegs) to smooth, light-coloured rocks near the water
surface. Pupae prefer depressions and cracks in dark-coloured rocks.
High-altitude species have a single generation a year whereas some species at
lower elevations may produce several; species probably overwinter in the egg.
Adults live only a few hours.
The Deuterophlebiidae contains
the single genus Deuterophlebia, found in widely separated regions of
the temperate northern hemisphere. North America has six described extant species,
all western. The known species in BC are Deuterophlebia personata Courtney,
known from the Hope region, Deuterophlebia inyoensis Kennedy and Deuterophlebia
coloradensis Pennak, both known from several areas of BC.
Family AXYMYIIDAE (Axymyiid Flies) [Figs.5]
Axymyiids are medium-sized
(5 to 6 mm long), rather stout flies with the general appearance of Bibio (Bibionidae), with which they can be confused. However, axymyiids have four
branches of the radial vein, versus 3 or less in bibionids, and 2 shiny spots
on the scutum, which are absent in bibionids. The large head bears compound
eyes divided into upper and lower sections by a line or groove; the eyes in
males meet dorsally, but are widely separate in females. There are three large
ocelli on a strong convex tubercle. The antennae are rather short, composed
of 16 small segments. The mouthparts are vestigial. The thorax is strongly arched
and bears a pair of shiny oval spots near the middle of the scutum. The thorax
has short pale setae; bristles or long erect setae are absent. The legs are
short and lack spines or long setae. The wing is longer than the body and, in
some species, has a faint pterostigma. Vein R2 is short, nearly perpendicular
to R2+3, ending in C at, or just past, the end of R1.
The medial vein is two-branched. The stem of the halter is very long.
Little is known about the
biology of the family; adults are seldom collected. The larvae live head-down in
cavities that they excavate in waterlogged, bark-free logs that are continuously
in contact with water or wet mud, apparently feeding on micro-organisms living
within the cavity.
The Axymyiidae is
restricted to the temperate northern hemisphere, where there are five described
extant species in three genera. In North America, Axymyia contains one
described eastern and one described western species. The western species, known
from Oregon, as well as an undescribed new species from Alaska may occur in
Family PACHYNEURIDAE (Pachyneurid Gnats) [Fig. 6]
Pachyneurid gnats are slender,
long-legged, long-winged flies. The head is small and globose with more or less
spherical eyes clothed in short setae; there are three ocelli, each on its own
tubercle. The antennae, comprised of 15 to 17 cylindrical or bead-like segments,
are shorter than the thorax, except in the males of Cramptonomyia, where
the antennae are as long as the abdomen. Thorax with the mesoscutum shallowly
convex; transverse suture weak; dorsocentral setae pronounced. The wing has
a distinct pterostigma. Vein Rs branches near the r-m crossvein; R2+3 is branched in Pachyneura, but is unbranched and connected to
R4+5 by an extra radial crossvein in other genera; discal cell usually
present. The abdomen is slender and longer than the wing.
Known larvae of
pachyneurid gnats bore in rotting wood. For example, larvae of the genus Cramptonomyia develop in logs of Red Alder along the Pacific coast;
larvae tunnel under the bark or just below the surface of bare wood, taking at
least a year to mature. Adults fly from February to April.
The Pachyneuridae contains
four described extant species in four genera. The Japanese genus, Haruka,
the eastern Siberian one, Pergratospes, and the North American genus, Cramptonomyia, are more closely related to each other than they are to
the fourth genus, Pachyneura, from Europe and Asia and are sometimes
placed in a separate family, the Cramptonomyiidae. Cramptonomyia spenceri Alexander lives in wet coastal forests from southern BC to Oregon. It is named
after its discoverer, George Spencer, the first entomology professor at the
University of BC.
Family BIBIONIDAE (March Flies) [Fig. 7]
March flies are dark, stocky,
somewhat setose flies, about 5 to 12 mm long. Females’ heads are rather flattened,
more elongate than males; the eyes are small and widely separated. The compound
eyes of males meet on top of the head, often covering much of it; the upper
two-thirds have large facets, the lower third has smaller ones. Ocelli are present
and prominent. The antennae are usually short with 9 to 12, normally rounded,
compact segments; Hesperinus is the exception; the antennae are long
with elongate segments. The scutum is prominent, domed. Femurs often swollen,
especially the front pair; front tibiae with apical spurs or rings of spines
in Bibio, Bibiodes and Dilophus. In the wing, R1 ends
just beyond the end of Sc; Rs simple or forked; crossvein r-m at or beyond the
middle of the wing. Medial vein is two-branched, CuA1 and CuA2 reach the wing margin and A1 is usually weak. There is frequently
In North America,
bibionids usually emerge in late winter or spring (thus the name March flies);
mating swarms can be enormous. The adult flies live only a few days; many visit
flowers and may be important pollinators, especially of fruit trees. Females,
aided by spurs or spines on the fore tibiae, burrow into moist earth to lay
eggs. Larvae scavenge in decaying organic material, rich soils and forest
litter. They often eat the roots of grasses and other plants and are frequently
numerous enough to damage cereal crops, vegetables, grass and other plant
The Bibionidae is a
common, worldwide family, with about 700 described extant species in six genera.
All genera occur in North America; the predominant genus is Bibio, with
53 extant species north of Mexico. BC has 21 extant described species in five
genera. Hesperinus brevifrons Walker, the sole member of its genus, is
boreal, ranging south to Colorado; it is unusually slender, with long antennae. Bibio is the most speciose genus in the province, with 14+ species. B.
xanthopus Wiedemann is common; adults emerge in February from grassy meadows
in Garry Oak woodland at Victoria. Bibiodes aestivus Melander is a
western species; it flies in June and July, later than many other species of
March flies. Five species of Dilophus are reported from the province. D. caurinus is a widespread one, ranging across the south; it is
distributed across the continent. The family apparently reached its zenith in
the Tertiary Period; Plecia is now predominantly tropical in
distribution, but in the Eocene, 50 to 60 million years ago, it was abundant in
what is now BC. The 21 named fossil species of Plecia in BC represent the
vast majority of insect fossils in Eocene shales from the interior of the
Rice, H.M.A. 1959. Fossil
Bibionidae (Diptera) from British Columbia. Bulletin of the Geological Survey of
Canada 55: 1-24.
Family MYCETOPHILIDAE (Fungus Gnats) [Fig. 8]
Fungus gnats are slender
to moderately robust flies, 2.2 to 13.3 mm long. Body usually dull yellow, brown
or black, but sometimes brightly coloured. Head usually flattened front to back,
and inserted well below level of upper margin of strongly arched thorax; eyes
usually densely setose, usually situated on lower part of head, and never meeting
above antennae; usually with three ocelli; frons between ocelli and antennal
bases usually bare; antennae inserted at middle of head, and with length varying
from scarcely longer than head to several times length of body; antennae beyond
basal two segments usually cylindrical, sometimes thickened basally and tapering
to apex, and usually composed of 14 segments; labella usually large and fleshy.
Thorax varying from compressed and deep to depressed and low; thoracic vestiture
variable, consisting of moderately strong bristles with apex bifed or otherwise
modified, scale-like setae, or very fine appressed or erect setae; setae or
bristles always present on pronotum, scutum and scutellum, but only occasionally
present on other thoracic sclerites. Wing veins often with setae; membranes
usually densely clothed with microtrichia, and often also with many macrotrichia;
R with three or fewer branches; usually with fork of M much longer than stem,
and lanceolate rather than bell-shaped. Legs with coxae long and stout; femora
usually slender, sometimes swollen, with variable vestiture; tibiae usually
slender, with variable vestiture, short setae arranged irregularly or in regular
rows, and with bristles variable; tibiae usually with long, strong apical spurs;
tarsi usually slender, sometimes with modified setae ventrally, or with some
segments swollen below in female; tarsal claws rarely simple, usually with one
or more teeth below. Abdomen usually broadest in middle; terga and sterna 1-6,
1-7 or 1-8 in male, and 1-7 in female well developed, but sternum 1 often reduced
in size. Male with sclerites of segments 7 and 8 short and telescoped into segment
6; terminalia usually symmetrical.
Mycetophilids are usually
found to be most abundant in humid or moist habitats in wooded areas. Many
larvae live in fleshly or woody fungi, on or in dead wood, under bark, or in
nests of birds or squirrels. Most or all of these are probably myctophagous,
hence the common name, but some members of the subfamily Keroplatinae seem to be
The family Mycetophilidae,
is now generally thought to be paraphyletic with respect to the Sciaridae. This
treatment of the families has been followed to allow for ease identification
of BC specimens to the generic level in McAlpine et al. (1981) There
are approximately 4300 described extant species in over 225 genera worldwide
of which about 825 species in 77 genera occur in north America. Over 200 species
of fungus gnats occur in British Columbia, with many apparently endemic.
Family SCIARIDAE (Dark-winged Fungus Gnats) [Fig. 9]
Dark-winged fungus gnats
are small delicate flies, 1.0 to 11 mm long, usually blackish, brownish or
yellowish in colour. Head usually ovoid in shape, higher than long; compound
eyes usually forming a dorsal bridge above antennal bases; frons with three
ocelli; basal two segments of antenna globular, rest of antenna with 14 segments
which are cylindrical, sessile or stalked; palps of one to three segments, the
basal segment usually reduced in size; first distinct segment often with a
sensory pit or with a group of sensory setae. Thorax with anterior pronotum
setose; posterior pronotum sometimes with a few setae; scutum with bristles of
variable length. Wings hyaline or smoky, sometimes reduced or absent; costal
vein ending between apices of R5 and M1. Tibiae with one
or two apical spurs; tarsal claws simple or toothed. Abdomen cylindrical, in
females, usually strongly tapered posteriorly. Male terminalia exposed, often
broader than rest of abdomen, and not usually rotated, but sometimes rotated up
to 180° during copulation.
Adult dark-winged fungus
gnats are usually found in moist places wherever fungus grows. Larvae generally
feed on decaying plant material, animal excreta, or fungus. The family is worldwide
in distribution with the exception of Antarctica. Some cosmopolitan species
appear to have been spread synanthropically. There are over 1800 described extant
species in about 90 genera worldwide with about 170 species in 18 genera known
from the Nearctic.
Family CECIDOMYIIDAE (Gall Midges) [Fig. 10]
Gall midges are very small
fragile flies, usually 1.0 to 5.0 mm long. Head with large eyes, holoptic or
nearly so in both sexes; antennae usually long, usually with 12 or 14 segments
beyond the basal scape and pedicel; mouth parts with generally fleshy labella,
one to four segmented palps and labrum, the labrum and labella occasionally
enlarged and styliform. Thorax about as long as high; mesonotum convex, usually
with two median and two lateral rows of setae. Wing with microtrichia, often as
scales, and occasionally with macrotrichia; wing veins generally weak, reduced
in number, costal vein usually continuous around wing, usually with a break just
beyond insertion of R5; R5 unforked. Legs usually long
with coxae conspicuous; tibial spurs absent; claws toothed or untoothed. Abdomen
elongate-cylindrical in male, elongate-ovoid in female; posterior end of female
abdomen often protrusible, sometimes very long, and in some groups variously
modified for piercing plant tissue.
Adults of the subfamily
Lestremiinae often fly in cool weather, and can be found at lighted windows at
night. The larvae are terrestrial and mycetophagous, usually found in decaying
vegetation and wood, in plant wounds, and in mushrooms.
Cecidomyiinae contains numerous gall-makers, hence the family’s common name.
However, other species are phytophagous in flower-heads or stems, without making
a gall. Some other species are mycetophagous, and there are some larvae that are
predaceous or parasitoids. As predators, species of this family feed on mites,
aphids, coccoids and other arthropods. Aphids and psyllids are usually the
insects attacked by the internal parasitoid cecidomyiids. There are over 5000
described extant species of gall midges worldwide with approximately 1200
species in about 170 genera occurring in North America
Family PSYCHODIDAE (Moth and Sand Flies) [Fig. 11]
Moth flies are small,
densely setose flies, with a rather moth-like in appearance, and with
characteristic short and erratic flight. Head with antennae longer than the
head, and sometimes longer than the body; antennae with 12 to 16 segments, each
segment usually with dense cupuliform whorls of setae, and with membranous
thin-walled sensilla that may be broad or slender, and that may be unbranched or
with two to many branches; eye bridge absent or incomplete; mouth part palps
with 3 to 5 segments, the next to last segment with a sensory pit or a compact
group of sensoria; proboscis usually very short, but in blood-sucking species
can be as long as height of head. Thorax with pronotum bare or setose; postnotum
bare; pleural sclerites variously setose or bare; transverse suture of scutum
not V-shaped; metanotum usually large and projecting over abdomen. Wings usually
broad, and held roof-like or flat over abdomen when at rest; longitudinal veins
of wings usually well developed; crossveins absent or restricted to basal half
of wing; costal vein continuing around wing. Abdomen with sternum 1 sometimes
unsclerotized; sternum 2 entire and divided into several sclerites, or
unsclerotized. Males with terminalia permanently inverted.
Adult flies are usually to
be found in moist protected areas, and are mainly active nocturnally. During the
day, adults usually rest in shaded habitats. Adult food habits are unknown,
except for the blood-sucking habit of female Phlebotomus. In the tropics,
species in this genus are the vectors of several diseases, such as
leishmaniasis. Blood-sucking adults, commonly called sand-flies, in North
America are usually associated with reptiles or small burrowing
Larvae of the subfamily
Psychodinae live in moist or subaquatic habitats, with a few species often found
in compost heaps and sewage disposal systems. Larvae of the subfamily
Phlebotominae live in soil, often in semi-desert areas. Other subfamilies have
larvae associated with fast streams and waterfalls, but these do not occur in
There are several thousand
described extant species of moth flies worldwide of which 112 species in 21
genera are recorded from North America.
Family TRICHOCERIDAE (Winter Crane Flies) [Fig. 12]
Winter crane flies are
small to medium sized, fragile flies with long slender legs. Head with three
ocelli, but with labrum reduced; antenna beyond basal two segments, elongate and
setaceous, with 16 segments, but segmentation obscure in distal segments. Thorax
with scutum flat, and with a V-shaped suture, incompletely developed in middle.
Wings with two strong anal veins that reach the wing margin, A2 much
less than half as long as A1, and strongly curved at apex. Legs with
tibial spurs present or absent.
Members of the
Trichoceridae are very similar to species of Tipulidae. However, in the latter,
the ocelli are absent or rudimentary, the scutum has a complete V-shaped suture
complete in the middle, and vein A2 in the wing is usually more than
half the length of A1, and relatively straight. In the Trichoceridae,
the legs do not fall off readily as in the Tipulidae, and females if they have
an elongate cercus associated with the ovipositor, this is curved downward,
whereas in the Tipulidae it is normally bent downwards.
As the common name
suggests, adults of Trichoceridae are found in the colder months of spring and
fall. On sunny days swarms of mostly male flies may be seen, but otherwise
adults often occur in dark places such as caves, mine shafts, cellars, hollow
trees and compost containers.
Larvae are scavengers, and
found in a wide variety of habitats, especially those with decaying leaves and
vegetables. They also occur in manure, fungi, stored roots and tubers, as well
as burrows of rodents.
The family is composed of
approximately 120 described extant species in four genera worldwide. Three genera
are recorded from North America, all of which occur in Canada and British Columbia.
The single species of Paracladura, P. trichoptera (Osten Sacken)
is confined to western North America, and has the basal tarsal segment very
short, and only about one-eight the length of the second. There is also only
one species of Diazosma, D. hirtipennis (Siebke). This
is a transcontinental species with a basal tarsal segment as long as the second,
and with glabrous eyes, but without tibial spurs. Several species of Trichocera occur in this province, of the 26 species recorded from North America. These
have the basal tarsal segment as long as the second, but the compound eyes have
setae between the facets, and tibial spurs are present.
Family ANISOPODIDAE (Wood Gnats) [Fig. 13]
Wood gnats are small to
medium sized flies, 2.0 to 10.0 mm long. Body slender and elongate, with long
slender legs. Head small, rounded and usually somewhat flattened; eyes
moderately large, rounded to ovoid, bare or setose; males with eyes separate or
meeting dorsally; frons with three ocelli, glabrous or with a few short, fine
setae; antennae about as long as combined length of head and thorax; scape and
pedicel short, but rest of antenna composed of 14 uniformly cylindrical
segments; mouth parts with palps short and 3 or 4-segmented. Thorax convex, with
pronotum greatly reduced. Wings moderately large and broad, lying flat over
abdomen when at rest; costal vein ending just beyond insertion of last branch of
R, usually near wing tip; M with two or three branches; anal lobe well
developed. Legs without strong spines; fore coxae long; tibia with apical spurs;
claws simple. Abdomen elongate and cylindrical, slightly convex dorsally, but
flattened ventrally. Male terminalia with rotation up to 180°.
Adults can commonly be found
on near larval habitats, often on bleeding tree trunks. They feed on nectar
and other liquids, and frequently occur at windows. Males can form small to
large mating swarms to attract females. Females oviposit on moist surfaces.
Larvae occur in decaying organic matter, and are common in fermenting sap and
There are about 100
described extant species in six genera worldwide of which nine species in three
genera are reported in North America. There are 5 described species in 2 genera
known from collections of BC Diptera.
Family SCATOPSIDAE (Minute Black Scavenger Flies) [Fig. 14]
Scatopsids are small and
rather robust flies, 0.6 to 4.1 mm long. Usually black, dark gray or brown in
colour, dull or shiny. Head laterally compressed, convex behind eyes and setose;
eyes occupying anterior half of head, usually holoptic, and with sparse or dense
setae; frons with three ocelli; antennae with scape and pedicel short, rest of 5
to 10 antennal segments short, often wider than long, usually pedicellate,
covered with setae and microtrichia; mouth parts reduced, with single-segmented
palp, but with larger labella. Thorax usually rather elongate and laterally
compressed; scutum with sparse short setae. Wings with rather reduced venation;
R5 usually unbranched, and veins posterior to R faint; wing membranes
covered with microtrichia, sometimes thickly; membrane and veins sometimes with
obvious setae. Tibial spurs absent on legs. Abdomen with seven obvious
pregenital segments; male terminalia sometimes rotated through 180°.
Little is known about the
biology of the Scatopsidae. The larvae of Scatopse notata (Linnaeus)
have been found in decaying plant and animal matter. Adults are often found
on flowers as well as on decaying plant and animal matter.
There are about 250
described extant species of scatopsids worldwide of which about 75 species in 19
genera have been recorded from North America. There are 15 species in 7 genera
known to occur in BC based on the published literature and collections of BC
Family CANTHYLOSCELIDAE (Canthyloscelid Flies) [Fig. 15]
Canthyloscelidae, includes the flies formerly referred to as the family
Synneuridae. Nearctic canthyloscelids are small slender and heavily sclerotized
flies, 2.0 to 3.5 mm long. Shiny and dark brown to black in colour. Head with
eyes meeting dorsally, ventrally narrowly separate to almost contiguous; frons
with three ocelli; antennae beyond basal two segments, 10 to 14-segmented,
bead-like, increasing distally with apical largest; mouth parts reduced, but
palps 4-segmented. Thorax rather slender, longer than high; pronotum reduced
medially, but with conspicuous postpronotal lobes; scutum narrow, strongly
arched, slightly tapering and more narrow anteriorly, sparsely covered with
short stiff setae; scutellum triangular and sparsely covered with short setae.
Wings long and slender, with anal lobe at most scarcely developed; membrane and
veins covered with microtrichia; costal vein strong, not reaching tip of wing,
but extending beyond posterior branch of R5. Legs moderately long and
stout; fore tibia with a small, but distinct spur; middle and hind tibia with
two short spurs; claws small and simple, at most with a basal tooth. Abdomen
long and slender, somewhat flattened dorsally, narrower anteriorly and widening
Little is known about the
biology of these flies in North America. Elsewhere larvae have been found living
in various kinds of decaying wood permeated by mycelia of various
Two genera, each with a
single species, have been reported from North America. Exiliscelis californiensis Hutson is reported from California and Oregon, while Synneuron decipiens Hutson is more widely distributed being recorded from British Columbia to Quebec,
and Alaska to Colorado.
Family PTYCHOPTERIDAE (Phantom Crane Flies) [Fig. 16]
contains moderately sized, slender, long-legged flies with long abdomens. The
head is transverse, tightly held against the thorax and the antennae are long,
with 15 (Ptychoptera) to 20 or 21 segments (Bittacomorpha,
Bittacomorphella). The mesonotum has the transverse suture forming a strong
loop rearward. The tibiae are spurred. The wings have Rs short and
R2+3 very close to R1; R4 and R5 present. M1+2 forked in Ptychopterinae, but not in Bittacomorphinae;
outer part of CuA2 strongly sinuous; only one anal vein present. The
halter has an unusual prehalter.
The most striking members
of the family are the two species of Bittacomorpha, the so-called
‘phantom crane flies’, which have the first segment of the tarsi inflated and
filled with tracheae. This feature enables the flies to sail on the breeze,
black and white banded legs outstretched. The striking habit gives them a
ghost-like appearance, especially when seen in the dappled shade of the forest.
The larvae live in wet mud and organic debris at the edges of forest streams and
pools; they have long, posterior breathing siphon.
consists of over 60 described extant species in only three genera. There are two
distinct subfamilies. The Ptychopterinae occurs in all regions except the
Australian and Neotropical; its sole genus, Ptychoptera, has many
species, including 11 in North America. The Bittacomorphinae contains Bittacomorpha, with two Nearctic species, and Bittacomorphella with four Nearctic and three eastern Asian species. BC has seven species in the
three genera: Ptychoptera lenis Osten Sacken, P. pendula Alexander, P. townesi Alexander, Bittacomorphella
fenderiana Alexander, B. pacifica Alexander, B.
sackenni (Röder), and Bittacomorpha occidentalis Aldrich.
Family DIXIDAE (Dixid Midges) [Fig. 17]
Dixid midges are fragile,
slender, yellow, brown or black, flies. Unlike their close relatives, the
mosquitoes, they have no scales on the wings or body. The compound eyes are more
widely separated above than below; ocelli are absent. The antennae are long,
16-segmented, with the second segment large and globose; the male’s antennae are
not plumose. The wings are large, with variable markings or hyaline;
R2+3 is strongly arched before it forks. The legs are long and
slender; the hind tibia is usually somewhat expanded apically and some tarsal
segments often have a small spine at the tip.
Dixid midge adults do not
bite, and it is not certain that they eat anything. They are short-lived. During
the day they rest, vertically and head up, on vegetation or the ground. Males
form swarms at dusk near vegetation along the edges of streams or ponds and
females fly into the swarms to mate; mating can also occur in daytime without
swarming. The slender larvae strain diatoms and other micro-organisms from the
water with complex mouthparts. They typically rest in a U-shaped position at the
surface film, usually against some substrate or plant near the water’s edge;
they swim by jerking the front half of the body from side to side.
The family consists of
approximately 200 described extant species worldwide; in North America 45
species are described in 3 genera. Dixa (8 species) and Dixella (7
species) are recorded in BC; the third genus, Meringodixa has one species
known only from California.
Family CHAOBORIDAE (Phantom Midges) [Fig. 18]
Phantom midges are closely
related to mosquitoes, but most do not bite. Adults are delicate flies,
measuring from about 1.5 mm to 10 mm long; they are usually pale yellow, grey or
brown. The compound eyes are separated in both male and female; there are no
ocelli. In males the antennae are strongly plumose; the second segment is large
and globose. The proboscis is short, extending only slightly past the clypeus.
In the wing, the radius has four branches, the three branches of vein Rs are
almost straight and parallel; M and Cu are two-branched. The wing’s hind margin
and most veins have scale-like setae; light and dark setae or pigment in the
membrane sometimes pattern the wings.
The family is aquatic and
adults are usually found around water, often in large mating swarms. They do not
bite. Most larvae (and all North American ones) are predators of other small
aquatic animals, including immature mosquitoes and members of their own family.
The antennae are prehensile and are used to grab prey. The larvae of Chaoborus are transparent (and thus called phantom midges); gas-filled
air sacs at each end of the body help them maintain their position in the water
of lakes and ponds.
The Chaoboridae is a small
cosmopolitan family, represented by 50 described extant species in six
There are three genera and
15 species in North America; all three genera are recorded in BC. The closely
related family Corethrellidae is mainly tropical, but extends into southern
and eastern North America; it is unknown in BC. Chaoborus has six species
in the province; Eucoethra contains a single species, E. underwoodi Underwood, which ranges across boreal North America and extends south in the
West to California and New Mexico. The two species of Mochlonyx are also
boreal and range into BC: M. velutinus Ruthe, and M. cinctipes (Coquillett).
Family CULICIDAE (Mosquitoes) [Fig. 19]
Mosquitoes are delicate,
long-legged, slender flies, 3 to 9 mm long and with scales usually clothing most
of the body, legs and the veins and hind margin of the wings. These scales vary
in colour and often form patterns that are useful in species identification. The
head is globose and the compound eyes are concave medially where they meet the
bases of the antennae. Ocelli are absent. The first segment of the antenna is
small, the second large and spherical and the other 13 are slender and bear a
whorl of setae; these setae are longer and more abundant in males than in
females. The mouthparts are elongate, stylet-like and enclosed in a sheath
formed by the labium. In the male, the maxillary palp is about as long as the
proboscis. The wings are narrow, long and lie flat above the abdomen when at
rest; there is no discal cell and the single vein R4+5 lies between
two branched veins – R2 and R3 in front and M1 and M2 behind.
Mosquitoes are common, widespread
and well-known insects. Few insect groups have been studied so much. Females
of most species bite and feed on the blood of vertebrates, but males do not,
and not all biting species feed on humans. Some mosquitoes transmit disease
organisms to humans and other animals – malaria, filariasis, yellow fever, dengue,
encephalitis and West Nile virus. Adult mosquitoes also pollinate many of the
plants that they visit, especially various native orchids. Larvae and pupae
are aquatic and live in marshes, ponds, pools, water-filled tree holes, man-made
containers, and other places where water collects. They come to the water surface
to breathe; most larvae eat organic debris and micro-organisms; a few are predators
The Culicidae is a large
cosmopolitan family of about 3560 described extant species in 42 genera;
approximately 190 species in 13 genera live in North America. BC has five genera
and 46 species. Anopheles contains three species in the province, Anopheles earlei Vargas, A. freeborni Aitken and A.
punctipennis (Say). The adults, with dark-spotted wings, take the typical
anopheline resting stance -- head-down, tail-up. The larvae, lacking a long
respiratory siphon, rest horizontally at the surface when breathing. The largest
BC genus is Aedes, with 33 species; females have a pointed abdomen;
Species overwinter as eggs. A. vexans (Meigen) is a widespread species in
Eurasia as well as North America; it is a mean biter and probably the most
annoying mosquito in Canada, at least in settled areas. In southern BC it ranges
from sea level to alpine. A. campestris Dyar and Knab is a yellow-brown
species breeding in the alkaline ponds of Interior grasslands; it is a strong
biter, even at midday. A. togoi (Theobald), probably introduced from
Japan, lives in rock pools just above high tide along the coasts of southern BC;
it was first found in Canada in the early 1970s. The three species of Culex overwinter as female adults. Culex pipiens Linnaeus, small and dull
brown, is common in houses and breeds in many aquatic habitats, the more
polluted the better. C. tarsalis Coquillett is common in southern BC, but
was rare before the 1950s; it is the principal vector of western equine
encephalitis. It habitually bites birds and is one of the potential vectors of
West Nile virus in BC. C. territans Walker prefers to feed on amphibians.
Females of the six Culiseta species in BC also overwinter. Culiseta
incidens (Thomson) is a large, brown, spotted-winged species that often
lives around humans; the females are often found in houses in the spring. There
is only one species of Mansonia in the province, M. perturbans (Walker). The larvae develop in marshes where they pierce the stems of aquatic
plants such as cat-tails with the respiratory siphon and take air from the plant
Belton, P 1983. The
Mosquitoes of British Columbia. British Columbia Provincial Museum Handbook No.
41. Victoria, BC. 189 pp.
Wood, D.M., P.T. Dang and
R.A. Ellis. 1979. The Mosquitoes of Canada (Diptera: Culicidae). Insects and
Arachnids of Canada, Part 6. Research Branch, Agriculture Canada. Ottawa, On 390
Family THAUMALEIDAE (Solitary Midges) [Fig. 20]
Thaumaleids are small,
stocky flies , about 2 to 3 mm long, mostly shiny yellow to dark brown in
colour. The head is small and globose, with the eyes meeting above in both
sexes. Ocelli are absent. The antennae are short, about as long as the head, and
project forward. The first two segments are large and spherical compared to the
next three, which are small and almost square; the last seven are linear. The
thorax is robust; the scutum is strongly arched dorsally and lacks a transverse
suture. The scutellum is large and pointed. The wing is broad, with the membrane
covered with macrotrichia in Trichothaumalea, these setae only on the
veins in Thaumalea. C reaches the wingtip; Rs usually forked to produce
very short, nearly vertical R2+3 (meeting R1) and a long,
curving R4+5 reaching the margin. M1, M2,
CuA1 and CuA2 normally strong and reaching margin. The
legs are rather slender and lack tibial spurs; empodia are minute and pulvilli
Adult flies are seldom
seen; they live around streamside vegetation. Larvae live on wet rocks (usually
on vertical surfaces in the shade) in cold streams. They scrape diatoms off the
rocks where the water flows as a film not thick enough to cover their bodies.
Pupae are collected in moss, wet leaves and mud on the stream
Five genera containing
about 120 described extant species are placed in the Thaumaleidae worldwide.
Most of the species are Holarctic; two of the genera and 8 species live in the
temperate parts of the southern hemisphere. There are two North American genera
– Thaumalea, with 23 species and Trichothaumalea, containing three
species. The there are 5 species of thaumaleids in BC based on the known
literature and collections of BC Diptera. Of these species, Trichothaumaleia
pluvialis (Dyar and Shannon) is known only from BC.
Family SIMULIIDAE (Black Flies) [Fig. 21]
Black flies are small stocky
insects, about 1.2 to 5.5 mm long. They usually are black or dark brown, but
colours also range to grey, rust, orange or yellow. The head is rather large
and round, with eyes meeting on top of the head in males, separated in females.
There are no ocelli. The antennae are short and thick, with 9 to 11 bead-like
segments. The thorax is often strongly arched dorsally, especially in males;
it is usually covered with short, dense, recumbent setae. The scutellum is also
prominent, more or less triangular and densely clothed in long setae. The legs
are short and rather stout; the front tibia has an apical spur, the others have
two. The first segment of the tarsus is elongate, that of the hindleg is often
swollen in males. The wing is broad with strong anterior veins and weak posterior
ones. Vein Rs is simple or has a long fork; rarely the fork is short and obscure.
There is a characteristic false vein (m-cu fold) that is usually forked apically,
but is unbranched in Parasimulium. Vein CuA2 normally is strongly sinuate.
Black fly females usually
have mouthparts structured to cut skin and suck blood, but in some females and
all males they are weak and only usable for imbibing fluids such as water and
nectar. However, not all species bite humans and some eat no blood at all. Those
that do bite can be serious pests of man, other mammals, and birds. Simuliid
bites are irritating and often cause infection and allergic reactions. Through
blood feeding, many species transmit parasitic disease organisms among birds and
mammals; the worst is the filarial nematode that causes human onchocerciasis in
the tropics of Africa and the New World. Larvae live in flowing water, attaching
themselves by the tip of the abdomen to a pad of silk they fix to submerged
objects. Most feed by filtering food out of the water with fan-like mouthparts;
some lack these labral fans (e.g., Gymnopais, Twinnia) and graze off the
The Simuliidae is a
relatively small, homogeneous family of almost 1800 described living species;
254 species in 13 genera are known from North America. Ten of these genera occur
in BC and contain 79 species, but a number more are recorded just outside the
provincial borders. Because of its wealth of ecological diversity, BC has, by
far, the greatest species richness of black flies of any province or territory
in Canada. The largest genus is Simulium, with 40 species. S.
baffinense Twinn is one of those black flies whose mouthparts are not able
to cut skin; it is a species of the far North and the Rockies, but the only BC
record is from the Atlin area. About 10 per cent of North American black flies
cannot bite; such species are mostly found at high latitudes or elevations.
Almost 40 per cent of blood-feeding American species primarily attack birds. For
example, S. annulus (Lundström), a holarctic fly, is known to feed only
on the Common Loon and is the only species known to regularly do so. It is not
yet confirmed from BC, but almost certainly occurs, because photographs have
been taken of black flies on loons in BC. Members of the Simulium venustum species complex, such as S. venustum Say, S. irritatum Lugger
and S. truncatum (Lundström) can be distinguished from each other only by
their chromosomes; they are the most fierce and abundant human biters in the
province. Nevertheless, although many of BC’s black flies bite people, we are
spared the hordes that plague Eastern North America. Prosimulium, with 15
BC species, is also diverse; the larvae prefer cold waters. The large, orange
females of P. fulvum (Coquillett) are conspicuous and are attracted to
humans; the species is among the most widespread and common of the genus in BC. P. esselbaughi Sommerman is another widespread biter in the group. There
are eight species of Helodon in the province; those that feed on blood
mainly attack birds. H. decemarticulatus (Twinn), widespread in the BC
interior, feeds on many species of woodland birds from Sharp-shinned Hawks to
Common Ravens. The arctic-adapted species of Gymnopais do not bite. There
are two species in BC -- G. dichopticoides Wood lives across northern BC
and down the Rockies and G. holopticoides Wood is known from the
Northeast. On the other hand, Twinnia nova (Dyar & Shannon) is a
vexatious biter in southern BC. The genus Parasimulium is endemic to the
wet forests of the North America’s Pacific coast and is the sole genus in the
Subfamily Parasimuliinae; it is the most primitive of the black fly groups.
Larvae live in subterranean waters such as underground springs and water flowing
beneath streambeds. Adults do not bite. There are five species, but only two are
known in BC, both recorded on Vancouver Island; P. melanderi Stone has
been collected in a cave. Four other genera have two or three species each in
BC: Greniera, Stegopterna, Tlalocomyia and Metacnepia; most
of the biting species in these groups feed on birds.
Adler, P.H., D.C. Currie
and D.M. Wood. 2004. The Black Flies (Simuliidae) of North America. Cornell
University Press, Ithaca, NY.
Family CERATOPOGONIDAE (Biting Midges, No-See-Ums) [Fig. 22]
Flies of the family
Ceratopogonidae are minute to small 1 to 6 mm long, (most in BC are about 2 mm
long) and slender to rather stout. The compound eyes usually meet, or almost
meet, on top of the head (but well separated in Leptoconopinae); they are
usually bare, but sometimes are finely setose. There are no ocelli. The antennae
have 8 to 15 segments, although vertebrate feeders have 13 to 14
(Leptoconops) or 15 (other genera); females have the last five segments
elongated (in the Leptoconopinae only the last one is differentiated) and most
males have plumose antennae. The proboscis is about as long as the head; most
females have serrate mandibles. A pair of humeral pits often occur near the
front edge of the mesonotum. The wing typically has one to three compacted
radial veins close behind the front edge of the wing and reaching the wing
margin before the wing tip; two median vein branches reach the wing margin;
crossvein r-m usually strong. The wings overlap over the abdomen when at rest,
often patterned with dark or light spots or patches. The females of predatory
Ceratopogoninae usually have at least one pair of raptorial legs with swollen,
spiny femora or with enlarged tarsal claws.
Biting midges live mainly
in moist habitats around the aquatic or semi-aquatic environments where the
larvae live. Most species of Culicoides fly at dusk, but those of some
genera, such as Leptoconops, fly during the day. Females of many species
suck blood to provide protein for egg maturation, and many are notorious for
both their biting and for transmitting disease. Their small size enables most to
crawl through the mesh of screens and, when large numbers of biting females are
present, avoiding them outdoors is difficult. Culicoides species are
vectors of filarial nematodes, blood protozoans and viruses such as bluetongue
in livestock. Culicoides, Leptoconops, Austroconops and
some Forcipomyia are the only genera that feed on vertebrates, usually
mammals or birds, but also reptiles, amphibians and even the amphibious mud
skipper fish of Southeast Asia. Many Forcipomyia drink the blood of large
insects such as dragonflies, katydids and butterflies, usually feeding from wing
veins. Other species kill small swarming flies and mayflies; some females eat
males of their own species. Dasyhelea and some other genera feed only on
nectar, and many others supplement their diet at flowers. Some are important
pollinators of cacao (from which chocolate is derived), rubber trees and other
plants. The larvae of the most diverse subfamily, the Ceratopogoninae, run the
gamut from burrowers in wet soil and manure to active swimmers in the waters of
large lakes and rivers. Many are carnivorous. Those of the Leptoconopinae live
in the soil and sand of arid habitats or the beaches of oceans and inland
waters, feeding on microorganisms. Forcipomyiinae crawl in moist places such as
moss mats or under bark, eating algae and fungi; Dasyheleinae wriggle in the
fluids of sap flows, tree holes and other small, wet habitats.
The fossil record of the
Ceratopogonidae is rich, especially in amber, and reveals that the family was
abundant and diverse at least 120 million years ago. Today there are 5600
described extant species in 103 genera, but this is probably much less than half
the actual total. There are 600 species in 39 genera known from North America
with BC having 114 species in 23 genera. Some of the more notable species
occurring in BC include, Atrichopogon epicautae Wirth which feeds on the
blood of meloid beetles, despite the fact that the blood contains the blistering
defensive chemical cantharadin. Forcipomyia bipunctata (Linnaeus)
is a setose, brown fly with a prominent yellow mark on the wing. The large
biting genus Culicoides is diverse in BC. At least 30 species occur,
including C. occidentalis Wirth and Jones, the main vector of bluetongue
virus, which has infected cattle in the interior; it is especially abundant
around saline ponds. Also common in the province are C. obsoletus (Meigen), a fierce biter of humans, and C. crepuscularis Malloch,
primarily an attacker of birds.
Family CHIRONOMIDAE (Chironomid Midges) [Fig. 23]
Chironomid midges are delicate,
small to medium-sized flies (1 to 10 mm long) with long, slender legs and narrow
wings; some superficially resemble mosquitoes, but lack the long proboscis.
Most are brown or black, but green, reddish and yellow species occur; many have
the abdomen and legs banded and some have patterned wings. The compound eyes
usually do not meet above; they may be bare or setose. Ocelli are absent, although
the frontal tubercles on some species may be modified ocelli. The antennae are
3- to 17-segmented, usually with more segments in males than in females; the
antennae are plumose in most males. The mouthparts are reduced, lack mandibles
and are non-biting. The thorax is convex or flattened above, the scutellum is
hemispherical; the postnotum is large and usually bare and marked with a median
longitudinal furrow. The legs often have the tarsus of the foreleg elongate
and sometimes strongly setose; the forelegs typically are held up off the substrate.
The wings lie flat or roof-like over the abdomen when at rest. The costal vein
usually is fused with R4+5 near the wingtip, but rarely reaches the
wingtip. The subcosta usually ends before reaching the costa. The radius is
three-branched, normally more strongly sclerotized than the posterior veins;
R2+3 is often weak, sometimes absent, and branches into R2 and R3 in the Tanypodinae. The medial vein is straight and unbranched,
meeting the wing margin near the wingtip. Vein CuA is forked at, or past, the
r-m crossvein and crossvein m-cu is present or absent.
Chironomid midges are
common and abundant – they are the most ubiquitous freshwater insects. Adults
are most active at dusk or at night and at sundown they often form mating swarms
that rise and fall over shrubs, rocks and other markers near water. Although
they do not bite, their sometimes enormous numbers can be a severe nuisance,
especially around lakeside homes and resorts. As in many groups of flies, the
immature stages of chironomids are more interesting than the adults. Larvae live
mainly in the fresh water of ponds, lakes and streams, but many species occur in
brackish habitats or the salty waters of desert and grassland alkaline lakes. A
few develop in the marine intertidal zone. Others live in wet soil and leaf
litter, in mammal dung and in pitcher plants. They are found from the mud in the
deepest lakes to the surface of stones in shallow pools and springs; they tunnel
in rotting wood and mine the tissues of aquatic plants; they live, sometimes
parasitically, on the bodies of mayflies, stoneflies, molluscs and other
organisms. Most chironomid larvae eat detritus and microscopic plants and
animals; most live on or in the substrate, usually in tubes made from substrate
particles bound with salivary secretions. Others, especially species in the
subfamily Tanypodinae, prey on macroinvertebrates such as other chironomid
The major groups of midges
generally prefer certain types of environments: thus, the Podonominae and some
other subfamilies are cold-adapted, living mainly in rapid streams; species of
the Orthocladiinae, too, mostly prefer cool waters, although some are common in
warmer habitats and the subfamily contains the only terrestrial chironomids. The
Chironominae and Tanypodinae are warm-adapted and most live in still waters,
often where oxygen levels are depleted. Most species of the former subfamily
live in or on the substrate and have oxygen-binding hemoglobin dissolved in
their blood (the so-called "bloodworms"); the Tanypodinae are free-living
predators and, when oxygen levels drop, they can swim to surface waters where
oxygen is more abundant. Through detailed analyses of these groups and their
preferred environmental conditions, species composition of chironomid larvae has
been used to classify lakes ecologically, to determine levels of pollution and
to examine the historical and prehistorical changes in lake systems.
The Chironomidae is a
large and cosmopolitan family of over 5000 species. Even Antarctica supports two
species and chironomids are among the most common and diverse insects in the
high Arctic. North America has almost 1100 described extant species in 205
genera; BC records include 151 species in 78 genera. In small saline lakes in
grasslands in the BC interior, chironomids can form distinct species
assemblages. The freshest ponds at Riske Creek on the Chilcotin plateau support
communities characterized by Cricotopus abanus Curran and Procladius
bellus (Loew); in the most productive, medium-salinity lakes, Einfeldia
pagana (Meigen) and Glyptotendipes barbipes (Staeger) predominate; in
the saltiest lakes (salinity above 3 parts per thousand) a Tanytarsus
gracilentus Holmgren and Cryptotendipes ariel (Sublette) association
is typical. The large Chironomus athalassicus Cannings is typical of, and
very abundant in, the most alkaline waters. In the province’s marine waters, Paraclunio alaskensis Coquillett, Saunderia clavicornis (Saunders), S. marinus (Saunders) and S. pacificus (Saunders) live
in the intertidal zone. Plant-associated midges are also significant in BC. For
example, Cricotopus myriophylli Oliver is an important grazer on the
growing tips of Myriophyllum spicatum, a pernicious aquatic weed in BC
lakes; the midge helps control the spread of the plant. Brillia retifinis Saether is a common member of the Orthocladiinae in coastal streams where it
plays a major role in the decomposition of conifer leaves that fall into the
water. The larvae mine in the needles of Douglas-fir and Western Yew, especially
after fungi have attacked the tissues.
Oliver, D.R. and M.E.
Roussel. 1983. The genera of larval midges of Canada (Diptera: Chironomidae).
Insects and Arachnids of Canada, Part 11. Research Branch, Agriculture Canada.
Ottawa, ON. 263 pp.
Family XYLOPHAGIDAE (Xylophagid Flies) [Fig. 24]
Xylophagid flies vary in
form, from stout and robust to slender and wasp-like, and range from 2 to 25
mm long. The body is often black, sometimes with yellow marks, but can be brown,
reddish or yellow. Conspicuous setae are lacking, although the scutellum of Coenomyia bears two strong spines. The head is spherical to hemispherical;
the compound eyes are broadly separated in females, but narrowly separated or
meeting dorsally in males. The surfaces of the vertex and face are even with
the compound eyes or only slightly depressed; in some species the latter is
sunken deeply below the compound eyes. The antennal flagellum is 7- to 8- segmented
in most genera, but has 20 to 36 saw-like or comb-like segments in Rachicerus. In Dialysis the flagellum, apical to the first segment, forms a thin
arista. The legs are slender, each tibia has one or two spurs; the empodia are
pad-like. The wings often have dark patches or spots. Except in Rachicerus the costal vein is continuous around the wing and cell m3 is open.
The medial vein is usually 3-branched and vein Rs arises before the base of
the discal cell. The abdomen, with 7 to 9 visible segments, is tapered to the
rear; the ovipositor is telescopic.
Xylophagids live in forest
habitats where adults feed on sap, nectar and other liquids. The larvae are
predators or scavengers in soil rich in organic matter (Coenomyia), under
tree bark (Xylophagus) or in decaying logs
The Xylophagidae contains
over 120 described, extant species world-wide, and 26 species in five genera in
North America. The family, although small, is poorly known in BC; only two
genera and four species are recorded. Xylophagus decorus Williston ranges
across North America; X. gracilis Williston is known from southern BC
south to California and Colorado. The former species is dark and slender,
ichneumon-like, and up to 15 mm long. Dialysis discolor (Loew) and D.
disparilis Bergroth range from BC to California along the Pacific coast. The
latter has a shiny black thorax and a yellow-brown abdomen banded in dark
Family XYLOMYIDAE (Xylomyid Flies) [Fig. 25]
Xylomyids are slender,
wasp-like or sawfly-like flies, 5 to 15 mm long, coloured in red, yellow and
black or with pale markings on a dark background. The body has no bristles and
is only inconspicuously setiferous. The head is hemispherical with the vertex
and face more or less flush with the eyes. The eyes are bare of setae and are
separate in both sexes. The antennae are 10-segmented, the eight segments of the
flagellum tapering apically. The thorax is short, oval and rather flat. The legs
are slender although the hind femur is sometimes thickened. The front tibia
lacks apical spurs, the others have one or two; the empodia are pad-like. The
wings are always clear and are folded flat over the abdomen when at rest. The
costal vein does not extend past vein M2; the medial vein is
3-branched and cell m3 is closed.
Adults are seldom seen,
but fly in wooded areas where they appear around rotting logs and stumps. The
larvae live under loose bark and in decaying wood where they are scavengers or
predators of small invertebrates. As in the Stratiomyidae, pupation occurs
within the last larval skin.
The Xylomyidae is a small
family closely related to the Stratiomyidae, with only about 130 described
extant species in four genera worldwide. Two genera -- Solva, with three
species, and Xylomya, with eight species, occur in North America. Only Xylomya is found in BC and the single known species in the province, X. parens (Williston) ranges along the Pacific coast from southern
BC to California. The abdomen is reddish and the top of the thorax has
crescent-shaped yellow marks on each side at the front.
Family STRATIOMYIDAE (Soldier Flies) [Fig. 26]
Both the scientific and
English names of the Stratiomyidae come from the "armed "thorax – many species
have spines, especially on the scutellum. The name is equally apt for other
reasons -- the metallic sheen and colourful bodies of many of these flies are
reminiscent of the armour and uniforms of soldiers. The adults are slender to
robust, 2 to 18 mm long; the body ranges from rather bare to densely setose,
but bristles are absent. These are often colourful flies – usually black, green,
blue or yellow, and often patterned. The head is as broad or broader than the
thorax, hemispherical to spherical, and sometimes protruding forward or downward.
The head behind the compound eyes is often expanded, especially in females;
ocelli are present. The compound eyes are bare to densely setose, widely separated
in females, joined or narrowly separated in males; in males the upper eye has
large facets. The antennae are variable; the second segment is often lengthened
(often creating elbowed antennae) and the flagellum (5 to 8 segments) varies
from simple and annulate to aristate. The proboscis is usually fleshy, sometimes
elongate and sometimes atrophied. The thorax is often characterized by pairs
of spines on the scutellum; occasionally spines also occur on the notum. The
legs are simple, tibial spines are rare and the empodia are pad-like. The wing
venation is distinctive. The small, short, sometimes almost circular, discal
cell is associated with a crowding of the thick, short, radial veins toward
the costa so that R5 reaches the wing margin well before the wing
tip. The costa does not reach past the wing tip. The veins arising from, and
posterior to, the discal cell are weak and tend to fade away. Viewed from above,
the abdomen varies in shape from almost cylindrical or stalked to ovoid or almost
round; it is always flattened, top to bottom, to some extent.
Adult soldier flies rest
and feed on flowers (for example, willows, hawthorns and cow-parsnip) and are
frequently found on grasses, sedges and other plants of wet habitats near marshes
and the margins of streams and ponds. They love to bask in the sun. Some of
the heavier flies, such as Stratiomys, can be sluggish and slow; others,
specially the slender Sargus, often hover. Larvae of the subfamily Stratiomyinae
(Stratiomys, Odontomyia, and others) are aquatic, living in a
wide range of waters, including harsh habitats such as hot springs and saline
pools. The Pachygastrinae (Zabrachia and other genera) live under tree
bark; many apparently are predators of beetle larvae, but probably also scavenge
in the wood. The other subfamilies develop in mostly terrestrial: habitats and
feed on rotting fruit and decaying vegetable matter, grass roots and vertebrate
dung, The larvae are elongate and flattened; the cuticle contains small calcium
carbonate plates, producing a shagreened surface. The pupa is enclosed within
the final larval skin; this foreshadows the puparium of the Muscomorpha, but
is actually an example of convergent evolution.
The Stratiomyidae is a widespread
family, with over 2650 species described worldwide. North America has 40 genera
containing 267 species; 18 of these genera and about 59 species are known to
occur in BC based on published records and collections of BC Diptera. One of
the largest American genera, Stratiomys, contains nine species in the
province -- S. barbata Loew, which lives over most of western North America,
and S. griseata Curran, a species found in the dry southern interior
of BC to Oregon and Utah, are among the more common ones. Species of Stratiomys have broad, strongly flattened, black abdomens with yellow markings. Seven of
the 12 Nearctic species of Caloparyphus occur in BC; most, such as C. crotchi (Osten Sacken), C. crucigerus (Coquillett) and C. mariposa (James) are Cordilleran species, ranging into the Southwest. Nemotelus,
most speciose of North American genera (40 species), has four species in the
province; including N. nigrinus Fallén, which is Holarctic and Neotropical.
The four species of Sargus in BC are small, elongate, metallic flies,
conspicuous when sunning on vegetation or near the decaying fruits or dung where
they lay their eggs. Sargus bipunctatus (Scopoli) is probably introduced
from Europe, but S. cuprarius (Linnaeus) is apparently Holarctic. S.
decorus Say and S. viridis Say are common transcontinental stratiomyids;
the former has a green thorax and a yellow and black abdomen, the latter is
metallic green or blue. Neopachygaster (1 species in BC) and Zabrachia (2 species in BC) develop under bark. N. occidentalis Kraft and Cook
ranges from BC to Oregon; Z. polita Coquillett, a transcontinental species,
is found in association with pine trees.
Family RHAGIONIDAE (Snipe Flies) [Fig. 27]
Snipe flies are mostly medium-sized,
4 to 15 mm long, with an elongate, tapering abdomen and rather long, slender
legs; the body is usually sparsely clothed in short setulae, but rarely are
there any enlarged bristles. Colours range from grey to brown to black, and
sometimes yellow or orange markings occur. The head is hemispherical with the
vertex usually on a plane with the compound eyes; the clypeus is strongly convex,
margined by deep grooves. The compound eyes meet above or are narrowly separated
in males, but are widely separated in females; they are bare, usually with the
upper facets enlarged in males. The antennae vary in form; the primitively 8-segmented,
tapering flagellum shows various reductions to an enlarged first segment bearing
a slender, usually unsegmented stylus or seta-like arista. The proboscis is
fleshy, but sometimes the mouthparts are developed for sucking blood. Legs lack
spurs on the front tibia, but have them on the middle, and usually on the hind
one; the empodium is pad-like. The wings are broad and elongate with strong
venation and a small calypter; many species have spotted wings. Vein R2+3 is characteristically short, meeting the costa close to the tip of R1.
In both sexes, the abdomen has seven visible segments; the ovipositor is telescopic.
Snipe flies are common in
woods, especially near wet areas. Adults usually perch on foliage and grasses;
the feeding habits of most are not well known, but presumably many are predators
of small insects. Most do not bite people, but some species of Symphoromyia are biting pests in the western mountains and along the Pacific Coast. In
these biting species is seen the last of the ancestral dipteran habit of
blood-feeding with the help of blade-like mandibles and maxillae;
vertebrate-biting habits that arose later in the evolutionary history of flies
rely on modified structures of the labium. Rhagionidae larvae live in decaying
wood and plant material, mosses, mud and debris where they eat small
The Rhagionidae is a
cosmopolitan family still in need of considerable study with 22 extant genera
and about 500 described species. In North America 105 described, extant species
are placed in eight genera, with BC records for about 24 species in six genera. Symphoromyia species are small grey flies, and some of them are annoying
biters, especially in subalpine habitats in BC. The first segment of the
antennal flagellum is characteristically kidney-shaped. In North America, 29
species are known; six of these occur in BC. S. johnsoni Coquillett is a
common species across the southern province. Rhagio contains at least
five species in BC; they have a rather large head and thorax, tapering abdomen
and broad wings. R. dimidiata (Loew) is black with a strong yellow band
across the middle of the abdomen; R. maculifera (Bigot) has a yellow and
black banded abdomen. Chrysopilus quadratus (Say) is one of about eight
species of this large genus in the province; this transcontinental species is
named after the rectangular brown wing spot. Ptiolina alberta Leonard is
a Rocky Mountain species and Bolbomyia wuorentausii (Szilady) ranges on
the coast from the Skeena Valley to southern Vancouver Island.
Family PELECORHYNCHIDAE (Pelecorhynchid Flies) [Fig. 28]
moderate-sized to large flies, 4 to 18 mm long. Mostly brown to black, the body
is often prominently setulose, sometimes colourfully so in Pelecorhynchus. The head is large, with a strongly convex face; the
compound eyes are large, unicolored, meeting above in males, separated in
females. Three ocelli are present. The first two segments of the antennae are
simple; the third (first of the flagellum) is the largest and is sometimes
elongate, and the others, up to seven in number, usually are reduced in size
towards the apex. The scutum is broad, almost as wide as long; the wings are
clear to smoky and have cell cup narrowly open at the margin and vein
A1 somewhat sinuate. The calypter is large. The legs are strong; the
empodium is pad-like.
Little is known of the
biology of adults, although some have been found feeding at flowers. The larvae
live in wet soil in swampy and marshy habitats where they eat earthworms and
other invertebrates. At least some Glutops larvae live in the sandy
bottoms of small, mountain streams.
Pelecorhynchidae contains about 46 extant species in three genera. The largest
genus is Pelecorhynchus, with 34 species confined to Australia and Chile.
North America has eight species in two genera; the four BC species are western
in distribution, ranging from the southern part of the province to California.
The most distinctive is Pseudoerinna jonesi (Cresson), a velvety black
fly with orange antennae and palps and smoky wings. Bequaertomyia is a
synonym of this monotypic genus. Glutops, with seven Nearctic and four
eastern Asian species, contains three species in BC: G. bandus Teskey, G. punctatus Wirth and G. rossi Pechuman.
Family OREOLEPTIDAE (Oreoleptid Flies) [Fig. 29]
First described in 2005
from the Canadian Rocky Mountains, the Oreoleptidae is a family closely related
to the Athericidae and Tabanidae. Adults are dull grey pruinose flies, 5 to
7 mm long. The eyes meet on top of the head in males, but are widely separated
in females; the upper two-thirds of the eyes have enlarged facets. The antenna
is 6-segmented, the last three progressively narrower and comprising an apical
stylus. The top of the thorax is covered with long, semi-erect setae; a prescutellum
is absent, but the subscutellum is present. The hind coxa bears a blunt peg
on the front face; in the wing, cell r1 is open. The first abdominal
tergite is undivided on the mid-line. In the female, the abdomen is telescoped,
with the genitalic segments not clearly differentiated from the others; the
cercus is 2-segmented, the first one strongly lobed below.
The few adult oreoleptids
ever seen were reared from collected larvae and pupae, and nothing is known of
the biology of the adult stage. The absence of mandibles in the female indicates
that these flies are not blood-feeders. The larvae, which bear two pairs of
long, slender prolegs on abdominal segments 2 to 7, are predators of immature
aquatic insects. Their flexible bodies allow them to crawl through the abrasive
substrates of torrential streams; they pupate in sand and gravel at the high
water line after spring run-off.
The Oreoleptidae is known
from a single genus, Oreoleptis, which lives in fast-flowing streams
and groundwater wells in the mountains of western North America from the Yukon
south to Montana and Idaho. A single species, O. torrenticola Zloty,
Sinclair and Pritchard, has been described from several sites in the Alberta
Rockies. All other records are of immature stages; it is not known if these
represent O. torrenticola or if additional species are also present.
In BC, larvae have been collected in Kootenay and Yoho National Parks.
Family ANTHERICIDAE (Athericid Flies) [Fig. 30]
Athericids are medium-sized
flies, 7 to 8 mm long, moderately setulose, but without enlarged bristles, yellowish
to black, with spotted or banded abdomen and yellowish, faintly banded wings.
Head dark, with the compound eyes widely separated in the female, almost meeting
dorsally in the male; the three ocelli borne on a tubercle. The antennae have
the first two segments globular, but the third is kidney-shaped and bears a
thin, elongate arista. The wing is large and broad; vein R2+3 is
short, ending together with R1; the branches of R4+5 are
splayed and enclose the wing tip; cell d is large, giving rise to three separate
branches of M; cell cup is closed. The legs are yellowish; the mid and
hind tibiae bear two apical spurs, but the front tibia has none. The empodia
Adults fly among
streamside vegetation; Atherix apparently feeds on honeydew, but female Suragina eat blood from humans and other mammals. Female Atherix lay eggs on leaves and branches overhanging the water and the flies remain there
and die; in some species, other females often lay eggs in the same mass,
resulting in a bulky lump of eggs and dead flies. In parts of California, at
least, aboriginal peoples collected and ate these rich sources of protein.
Hatching larvae fall into the water, becoming fierce predators of midge and
mayfly larvae in stream riffles and underwater vegetation.
The Athericidae is a small
cosmopolitan family with eight genera and about 70 species worldwide. Athericids,
until recently, were considered snipe flies, but are probably more closely related
to the Tabanidae. In North America, two genera occur -- Atherix (four
species) and Suragina (1 species), but only the former occurs in Canada. A. variegata Walker is the only described species known to occur in BC,
but A. pachypus Bigot probably also occurs, at least in the southwest
-- it is recorded from the mountains just south of the US border.
Family TABANIDAE (Horse Flies and Deer Flies) [Fig. 31]
Horse flies and deer flies
are medium-sized to large (5 to 30 mm long), rather stout, large-headed flies,
black, grey or brown, often coloured in orange or yellow; their bodies are more
or less finely setulose, but lack enlarged bristles. The large compound eyes,
often brightly coloured, iridescent, striped or spotted, are separated in females,
but meet dorsally in males; the antennae are 5 to 11-segmented, the flagellum
consisting of a large basal segment and 2 to 8 small annular segments apically.
The proboscis is strong and rigid, with knife-like mandibles and maxillae in
females of biting species. The large thorax bears stout legs; the front tibia
lacks apical spurs, but these occur on the middle tibia and are present or absent
on the hind one. The empodium is pad-like. The wing bears large calypters. The
venation is rather primitive and uniform; the costa extends around the wing
margin and the radius has four branches. A distinctive feature is the splayed
veins R4 and R5, which widely straddle the wingtip. The wings are often darkened
and patterned distinctively. The abdomen is broad, often strikingly patterned;
seven segments are visible.
Horse flies and deer
flies, because of their fierce biting habit, are familiar to most people who
spend time in the summer, outdoors, away from cities and towns. Indeed, these
flies are well studied because of their medical and veterinary significance.
Apart from the annoyance and loss of blood suffered by humans, domestic and wild
animals that the females bite, tabanids are also vectors of microorganisms that
cause tularemia, anthrax, anaplasmosis and other diseases. Normally, adults are
active only in bright sun on warm, windless days; both females and males visit
flowers to feed on nectar. Some species require no blood meal to mature the
eggs, but most females suck blood from warm-blooded animals, at least after the
first batch of eggs is laid. The compact egg masses are laid are laid on plant
stems or leaves above the larval habitat. The larvae of most species live in the
wet soil of marshes, fens, bogs, and along the margins of ponds and streams. A
few live in the beds of fast flowing streams and some develop in dry soil.
Apparently, most are predators of invertebrates, although Chrysops larvae
may feed on plant matter in mud.
Worldwide in distribution,
the family Tabanidae consists of about 4,200 named species in 201 genera; in
North America these numbers are 316 and 25, respectively. BC has 62 species
in eight genera. There are three subfamilies: the Chrysopsinae, with hind tibial
spurs and an antennal flagellum with five or fewer segments; the Pangoniinae,
with hind tibial spurs and eight or nine apparent segments in the flagellum;
and the Tabaninae, lacking apical spurs on the hind femur. In BC the Chrysopsinae
contains the genera Silvius (one species) and Chrysops (15 species). S. gigantulus Loew has a yellow-grey thorax and an orange abdomen; it
occurs from southern BC to Baja California. Chrysops is a speciose and
familiar genus. Deer flies are insects of open woodland, most diverse in north
temperate regions, where members of the deer family are common. When biting
people, they usually attack the head and neck. Most species in BC are about
1 cm long with golden or green eyes, brown-banded wings and orange abdomens
marked with brown. C. excitans Walker, the most common species in boreal
Canada, is abundant throughout BC. C. ater Macquart is also boreal, but
is restricted to east of the Rockies in the province. C. asbestos Philip
and C. noctifer Osten Sacken are common Cordilleran species and C.
discalis Williston is abundant around the saline lakes of interior grasslands.
In BC the Pangoniinae
contains Apatolestes and Stonemyia, both rather rare; the former
is completely western in distribution, the latter has species in eastern as well
as western North America. In Canada, A. comastes Williston is recorded in
Canada only from Robson, BC and S. californica (Bigot) is restricted to
the Okanagan Valley. The subfamily Tabaninae, in BC, is dominated by the
speciose and physically large northern genus Hybomitra – the species are
usually 10 to 20 mm long, black, and usually with orange or grey on the abdomen
and green-banded eyes. Twenty-nine species of these horse flies are recorded in
the province. Hybomitra affinis (Kirby), H. frontalis (Walker) and H. zonalis (Kirby) are abundant transcontinental flies, occurring
throughout BC; H. captonis (Marten) is one of the most common Cordilleran
species, ranging from BC to California. H. sonomensis (Osten Sacken) is
restricted to the coast in BC, where it is abundant. The genus Tabanus contains our largest horse flies. The two biggest of the ten species in BC
are T. aegrotus Osten Sacken and T. punctifer Osten Sacken, which
reach 24 mm in length; the former is all black, the latter is black with the top
of the thorax grey. Both are restricted to BC in Canada. Haematopota is a
speciose genus of over 300 species that has evolved with the mammal family
Bovidae – most occur in Africa and Asia, and North America has only five
species. Of these, only the western H. americana Osten Sacken lives in
BC; the body is black marked with grey and the wings are speckled grey. Atylotus calcar Teskey is a denizen of saline habitats in grassland; A. insuetus (Osten Sacken) lives in forest wetlands. The golden haired A. tingaureus (Philip) is especially common in coastal BC
Teskey, H.J. 1990. The
horse flies and deer flies of Canada and Alaska (Diptera: Tabanidae). Part 16.
The Insects and Arachnids of Canada. Publication 1838. Research Branch,
Agriculture Canada, Ottawa, ON.
Family NEMESTRINIDAE (Tangle-veined Flies) [Fig. 32]
Tangle-veined flies are
medium-sized to large, stocky flies, often strongly setulose and bee-like, but
without enlarged bristles. The colours are variable, often black, brown, yellow
or white and frequently the thorax and abdomen are striped and banded, respectively.
The head is large, usually about as wide as the thorax; the compound eyes meet
dorsally in most males, but are separated in females. In males, the upper compound
eye facets are enlarged. Three ocelli are present. The antennae are small with
the first three segments about equal in size and a terminal stylus, usually
of three segments. The proboscis is vestigial, or short and fleshy (e.g., Trichopsidea),
or longer than the head, slender and sclerotized for flower feeding (e.g. Neorhynchocephalus).
The legs are slender and lack tibial spurs; the empodium is pad-like. The wings
are rather narrow, sometimes tinged with brown; the complex venation gives the
family its common name. The veins in the apical half of the wing are parallel
to the front and hind margins of the wing and usually end at the wing margin
before the wing tip. The so-called diagonal vein is present, obliquely crossing
the middle of the wing; it consists of parts of Rs, R4+5, crossvein
r-m, M1-M3, and CuA1. The abdomen is conical
or widest near the middle; the ovipositor is either a telescoping tube or a
sabre-shaped structure formed from the elongated cerci.
Adult tangle-veined flies
are fast fliers and are most often seen at flowers or hovering, motionless, with
a high-pitched hum. The adults of several tropical species are known to be
pollinators of plants such as orchids. The few species that have been studied
develop as parasites of grasshoppers and beetles. Hirmoneura species of
the US Southwest attack the larvae of scarab beetles; elsewhere it also
apparently feeds on long-horned beetles. The other two genera occurring in North
America, Neorhynchocephalus and Trichopsidea, parasitize
grasshoppers. Thousands of eggs are laid in crevices in posts and trees; these
hatch into tiny, active larvae, which search for hosts. Apparently they are
often dispersed by wind. Once the larva enters a host insect it develops into a
maggot (hypermetamorphosis), producing a respiratory tube (lacking in Hermoneura) that links the spiracles at the larva’s rear end to the
outside air. The larvae parasitizing grasshoppers feed mainly on the fat body
and ovaries of the host. Mature larvae overwinter in the soil.
The approximately 300 named
species of Nemestrinidae worldwide are arranged in 23 genera. The majority of
genera and species live in the southern hemisphere, and only six species in
three genera are recorded in North America. Two species live in Canada; both
occur in the grasslands of the Thompson and Okanagan valleys -- Neorhynchocephalus
sackenii (Williston) and Trichopsidea clausa (Osten Sacken). The
former has been recorded from Osoyoos to Kamloops, the latter from Kamloops
to the Chilcotin. If not rare, they are, at least, seldom seen. Both species
are clothed in pale yellow setae, which is long and dense in front, but shorter
on the abdomen, where it forms a band on the rear margin of each segment. At
Riske Creek in the Chilcotin, T. clausa is recorded laying eggs in the
holes and cracks in old telephone poles that ran through an egg bed of Camnula
pellucida, a common grasshopper of BC roadsides and probably the host of
the flies. Green-eyed N. sackenii, with its long proboscis, probes in
flowers for nectar.
Family ACROCERIDAE (Small-headed Flies) [Fig. 33]
Adult small-headed flies
are bizarre often, as the common name suggests, with tiny heads dwarfed by a
grotesquely inflated thorax and abdomen. There is significant variation, however;
they range from 2.5 to 30 mm long and boast a range of colours from metallic
blues, greens and purples to browns and blacks mixed with yellows and whites.
The body can be nearly bare, but usually is covered with fine setulae; there
are no enlarged bristles. The head is usually small and globose, fixed low on
the thorax, and consisting mostly of the compound eyes, which meet dorsally
in both sexes. There are normally three ocelli. The antennae are 3-segmented;
the first two segments are short and round, the third (flagellum) varies from
long and sword-shaped, awl-shaped or thread-like to short and spoon-shaped with
long apical setae. The mouthparts are either vestigial, partly developed into
a short tube, or well developed into a long sucking proboscis. The thorax is
often humpbacked, sometimes flat; the legs are normally simple, but some species
have swollen femora. The empodium is pad-like, but is sometimes reduced or absent.
The wing is variable in shape and venation; it is usually clear, but sometimes
is infused with brown. The lower calypter is unusually well developed. In the
males of some taxa (especially Pterodontia) a striking costal thickening
and projection occurs at the junction of Sc with R1 and R2+3.
The Sc reaches the middle of the wing or farther; R2+3, when present,
usually ending in the wing margin; an extra crossvein r-m sometimes present,
forming cells R4+5 and R5. The venation may be so reduced
(as is often the case in Ogcodes) that there are no longitudinal veins
behind R1. The abdomen is usually globose, but can be globose-elongate
(for example, Eulonchus), tapered, laterally compressed or wasp-waisted.
Acrocerid genera that have
a well-developed proboscis (e.g., Eulonchus, Lasia) visit flowers
for nectar, and species of Eulonchus are important pollinators of some
wild flowers. Acrocerid larvae are internal parasitoids of spiders. An adult
female lays several thousand eggs in the vicinity of a host population – the
oviposition site depends on the genus, for example, Ogcodes lays eggs on
dead twigs, Acrocera on grass stems, Eulonchus on the ground. Like
the first instar larvae of the Nemestrinidae, those of acrocerids crawl and jump
around, searching for a host. Finding a spider, the larva burrows inside and
takes up residence in the book lungs where it can breathe outside
Usually, the larva rests
there until the spider is almost mature, then moults twice; the third and final
larval stage is maggot-like and rapidly devours the liquid contents of the
spider. Emerging, the larva pupates nearby, often in the host’s web.
The Acroceridae contains
about 520 described extant species in 50 genera; there are seven genera and
61 named species in North America. The 12 species recorded in BC are from five
genera. The most diverse is Ogcodes, one of only two cosmopolitan genera
and, with 90 species, the most speciose acrocerid genus in the world. Hosts
include a wide range of spiders in families including the Lycosidae, Agelenidae,
Thomisidae, and Clubionidae. BC reports five species, most of which are blackish
with white bands on the abdominal segments. The most widespread is O. eugonatus Loew, which ranges from Canada to Mexico. Acrocera species are small
black or brown flies, often with the abdomen coloured in orange or yellow. The
four BC species range more or less transcontinentally: A. bulla Westwood
is a very small acrocerid, some specimens being only 2.5 mm long; A. convexa Cole has a bright orange abdomen that gives it the appearance of a ladybird
beetle when resting on a grass stem; A. melanderi Cole has broad yellow
bands on a dark abdomen; A. orbicula (Fabricius) is Holarctic and has
black bands on a yellow abdomen. Turbopsebius diligens Osten Sacken lives
from BC to Mexico; males have clear wings, but those of females are usually
darkened. Pterodontia misella Osten Sacken, a parasitoid of Pardosa wolf spiders, occurs across southern BC; it ranges south to California and
Utah. Males have the abdomen patterned in yellow-orange, but the females are
all black. Eulonchus is predominantly a western genus; members are easily
recognized by their large size, colourful metallic body and long proboscis.
The single BC species, metallic green or blue-green and 15 mm long, is usually
named in collections as E. tristis Loew; this, BC’s largest acrocerid,
Family THEREVIDAE (Stiletto Flies) [Fig. 34]
Stiletto flies are slender
to rather robust, small to medium-sized flies (2.5 to 15 mm long); the English
name perhaps relates to the pointed abdomen of many species. The colour of the
cuticle ranges from black to yellow, but the body is partly, to completely,
setulose and is often patterned with silvery or white tomentum. The wings are
often banded or spotted. The head is hemispherical, without a depression between
the compound eyes; the compound eyes are separate in females, but meet dorsally
in most males. There are three prominent ocelli. The antennae sometimes arise
from a prominent protuberance and the first segment is often enlarged (as in Tabuda); the first segment of the flagellum is the largest and one or
two more form a small stylus, which bears a bristle, often tiny. Prominent bristles
are usually present on the thorax and legs, which are usually long and slender;
the empodium is bristle-like or absent. The wing venation is rather uniform;
vein R4 is long and usually sinuate; cell d is elongate with M1,
M2 and M3 arising from the apex; cell m-cu present; pterostigma
and calypter usually well developed. The 8-segmented abdomen tapers rearward
and is convex to flattened above; acanthophorite spines are usually present
Some therevids resemble
small asilids in form and behaviour, although the structure of the head is
distinctly different. The deep cleft between the eyes of robber flies is absent
and, because the proboscis is built for sponging rather than piercing, stiletto
flies do not prey on other insects. Other species look like rhagionids and some
mimic wasps. Adults frequent a wide variety of habitats – forest openings,
meadows, stream margins and dry areas such as beaches or sand dunes. They rest
in the sun on different substrates, often depending on the species or genus –
sand, rocks, logs, leaves, tree trunks, and so on. The elongate, snake-like
larvae are predaceous in sand and loose soil, under dead tree bark and in
decaying fruit or fungus where they attack invertebrates, especially the larvae
of click, scarab and darkling beetles.
The Therevidae is a cosmopolitan
family containing over 1000 described species; about 151 species are known in
28 genera in the Nearctic. The BC the fauna is poorly known – there are about
16 species in nine genera recorded in the literature and known from collections
of BC Diptera. With 29 described species in North America, Thereva is
a genus of the mountains and boreal forests. Thereva brunnea Cole and T. frontalis Say are BC species that range south into the US northwestern
states; T. nigripilosa Cole has been collected in BC only. Most Pandivirilia species live in the forests of the western mountains where some, at least,
develop in conifer logs. Pandivirilia limata Coquillett is a large grey
species, 12 mm long that lives from BC south to California and Colorado; P.
bussi (James) ranges north to the Yukon. Spiriverpa contains some
common species of sandy habitats – S. cinerascens Cole and S. cockerelli (Cole) are among them. Tabuda planiceps (Loew) has the base of the antenna
prominently thick and setose and the front edge of the wing darkened; it is
mainly a coastal species, occurring from BC south to California. At least one
species of the forest-inhabiting genus Psilocephala occurs in BC, but
the group requires study in order to resolve the identity of the province’s
Family SCENOPINIDAE (Window Flies) [Fig. 35]
Scenopinids are sturdy,
small to medium-sized flies usually not much more than 5 mm long. The body is
bare or setulose, but lacks enlarged bristles; it is usually dark in colour,
but is sometimes marked with white or yellow. The head bears prominent compound
eyes, which occupy most of the head and usually meet dorsally in males, but
are separated in females. The upper facets of the compound eyes are enlarged
in males Three ocelli are present; the vertex is level with the compound eyes;
a prominent flange is often present behind the eye, especially in some females.
The three-segmented antennae arise close together; the third segment (flagellum)
bears a peg-like stylus and varies from long and slender to short and oval,
often with a slightly forked tip. The facial area around the mouthparts is deeply
recessed. The thorax is long and moderately convex, pruinose and sparsely covered
with short to long setulae or scale-like setulae. The scutellum has no bristles.
The legs are short; empodia are absent. The wings have prominent radial veins,
R2+3 is usually short, ending close to R1; R4+5 forks and R4 ends well before the wing tip; cell r5 is
open to the wing tip and is narrowed, or is closed and stalked. The abdomen
is broad and flattened or cylindrical, with seven easily seen segments in the
male, eight in the female; most segments are subdivided by a transverse groove.
Larvae are predators of
insects. Those of window flies, a few species of Scenopinus, prey
especially on the larvae of household pests of cloth, wood, stored food and
pets, including clothes moths, dermestid beetles, powder-post beetles and fleas.
After emergence, the adults appear on the windows of buildings, trying to escape
to the outside. In more natural situations they probably live in bird and mammal
nests. Other species are recorded in decaying wood, in fungi, in the galleries
of wood-boring beetle larvae, in termite nests, and in the nests of woodrats and
The Family Scenopinidae is
world wide in distribution, with about 414 species described. Many of these (157
species in nine genera) are from North America, especially the arid southwest.
The most diverse of these genera are Scenopinus (50 species), Brevitrichia (45 species) and Pseudotrichia (36 species). There
are nine species in two genera known from the literature and from collections of
BC Diptera to occur in the province. Perhaps the most familiar are Scenopinus
fenestralis (Linnaeus) and S. glabrifrons Meigen, originally from
Europe, but now widespread over much of the globe, having been distributed
everywhere by commerce because of their association with household
Family MYDIDAE (Mydid Flies) [Fig. 36]
Mydid flies are medium-sized
to extremely large (Mydas heros of Brazil, with a length of 60 mm and
a wingspan of 100 mm is probably the world’s largest fly), sparsely covered
in short setulae and lacking enlarged bristles except on the legs. Body colour
is variable, and usually is some combination of black, yellow, red or white.
The head is wider than high and the face is usually swollen and setose, but
is flatter in the ancestral subfamilies. Most species have long, 4-segmented
antennae with the two segments of the flagellum especially elongate; the second
flagellar segment is normally clubbed and usually bears a tiny apical spine.
The more ancestral species have a 1-segmented flagellum. The compound eyes are
large, almost always with uniformly small facets; there are three ocelli. The
proboscis is well-developed, usually short, but can be up to five times longer
than the head (for example, in Rhaphiomidas). Compared to the other legs,
the hind leg is frequently longer and stouter, with the femur usually swollen
and bearing spines on the lower surface; the hind tibia often has an apical
spur or bristles. Unlike in the Asilidae, there is no empodium and the pulvilli
have one rib instead of two. The wings can be clear or washed with yellow, orange
or brown. The wing venation is distinctive, with most veins usually ending in
the front margin of the wing. Vein Rs is very short and cell br is extremely
long; all radial veins, M1, and sometimes even M2 end
before the wing tip. Cells r4, r5 and m1 (when
present) therefore curve forward, parallel to the hind edge of the wing tip;
cell m3 lies parallel to the hind margin of the wing. The abdomen
is cylindrical and taper rearward in males, but in most females is widest in
the middle. Male tergite 8 almost always has a deeply concave hind margin. In
most females (except, for example, Mydas), tergite 10 is developed into
acanthophorites bearing a circlet of strong blunt spines.
Mydids live mostly in warm
habitats such as dry, open woodlands, grasslands and deserts. Adults, with their
long antennae and colourful bodies, often resemble wasps and probably mimic
them. They have been implicated as predators, but there is little evidence for
this habit; probably most feed at flowers and those with atrophied mouthparts
may not feed at all. Although little is known about the larvae, some species are
known to prey on beetle larvae in rotting wood and sandy soil.
The Family Mydidae is widely
distributed, especially in dry tropical, subtropical and Mediterranean climates.
It is an old and scattered family of about 360 species in 54 genera, long past
its heyday, and has probably suffered much extinction. It dates back at least
to the Jurassic, and like the Apioceridae, the ancestral subfamilies of the
Mydidae (Raphiomidinae and Megascelinae) show relationships and geographical
distributions related to the break-up of Gondwanaland. These ancestral groups
have only recently been transferred from the Apioceridae to the Mydidae. There
are 51 species in eight genera in North America. Two species barely range into
Canada – Mydas clavatus Drury in southern Ontario and Nemomydas pantherinus Gerstaecker in BC’s southern Okanagan Valley. The latter species, with its yellow
and black-banded abdomen is easily mistaken for a wasp in the dry, sandy grasslands
of Oliver and Osoyoos. It is distributed in the intermontane grasslands and
dry forests south to California.
Family APIOCERIDAE (Flower-loving Flies) [Fig. 37]
Adult flower-loving flies
are robust, medium sized flies, usually about 12 to 35 mm long. The body is bare
to moderately setulose; the colour is black or brown, often with extensive grey
or tan tomentum and pruinosity creating patterns, especially on the abdomen. The
head is short and wide; the compound eyes in both sexes are widely separated by
a shallow depression. There are three ocelli. The antennae are short and
4-segmented; the first segment of the flagellum is usually pear-shaped and the
second is short, cylindrical and acute. The palps are 2-segmented; the proboscis
is large and fleshy. The stout mesothorax bears bristles on the sides and rear.
The legs are unspecialized, but usually there are a few bristles on all
segments; the empodium is bristle-like. Apiocerid wings are relatively short
with venation resembling that of mydid flies. Veins R2+3 join
R1 before the wing margin; R5 and M1 curve
forward to join the margin before the wing tip. Crossvein r-m lies at about the
midway point of the discal cell. The abdomen is elongate, tapering rearward, and
has eight visible segments; the male genitalia are enlarged and club-like and
the female has acanthophorite spines.
Flower-loving flies are
inhabitants of dry, hot places, especially where there is a nearby source of
water. They especially like the edges of sand dunes where there is a sparse
cover of plants. The best place in BC to find them is the extensive sandy
habitat on the east side of Osoyoos Lake, but they occur at least as far north
as the patches of grassland growing on sandy loam at Penticton. Females lay eggs
in sandy soil at the base of plants. The term "flower-loving flies" is a
misnomer, although it is firmly established in books – most of these insects
seldom visit flowers. They spend much of their time walking or running on open
sand or soil; when the temperature is high they make fast runs and short flights
between shaded spots under plants. Flight is often noisy. The mouthparts are
sponging -- the flies are attracted to water in the soil and imbibe honeydew
from beneath aphid-infested plants. The slender larvae apparently prey on
invertebrates in the soil.
The ancestral mydid
subfamilies Raphiomidinae and Megascelinae have recently been transferred from
the Apioceridae to the Mydidae, leaving Apiocera, with 137 described
species, as the only apiocerid genus. This group is divided into four subgenera
from four discrete geographical regions: western North America, southwestern
South America, South Africa, and Australia. Evidence suggests that the family,
like the Mydidae, arose in Pangaea before the middle of the Jurassic; its modern
disjunct distribution resulted from the subsequent break-up and movement of the
continental plates. The North American subgenus is the most ancestral; the
region (including northern Mexico) has 58 named species. The single Canadian
one, Apiocera barri Cazier, is known in the country only from the dry
grassland and shrub-steppe of the southern Okanagan Valley. It ranges south to
Family ASILIDAE (Robber Flies) [Fig. 38]
Robber flies are named after
their predatory habits – they attack and devour other insects. The body form
varies widely, from delicate and slender to heavy and stout, from almost bare
to bristly or setulose. Some are tiny flies only 3 mm long, but others are gigantic,
over 50 mm long. Colours range from browns, greys, silvers and blacks to colourful
patterns of contrasting blacks, yellows and reds. Males of some species have
additional ornamentation such as the expanded silver abdominal tip in Nicocles,
the striking white abdomens of Efferia and the decoration on the tarsi
of many Cyrtopogon species. The compound eyes are large usually rather
flattened from front to back; in most species the broad forward-facing area
has enlarged facets. The compound eyes are well separated dorsally in both sexes
by a distinctive hollow. The ocelli are prominent, usually placed on a tubercle.
Varying from flat to strongly protuberant, the face bears a characteristic tuft
of setulae or bristles, the mystax. The antennae are erect, usually 4-segmented.
The first segment of the flagellum is elongate or oval, the stylus is normally
2-segmented, but may be 1-segmented or apparently absent; it is prominent and
seta-like in the Asilinae. Both sexes have stabbing and sucking mouthparts developed
into a proboscis -- paralyzing saliva is injected through the needle-like hypopharynx
(tongue), which is sheathed in the prominent labium. The thorax is prominent
and powerful and usually bears distinctively arranged bristles. The legs are
strong and raptorial, frequently with numerous bristles; the empodium is bristle-like,
but is lost in some Leptogastrinae; the pulvilli are also lost in the latter
subfamily and a few other genera. The wings are sometimes coloured or spotted.
The venation is not much modified and vein R always has four branches, with
R2+3 unbranched. However, R2+3 joins R1 before
the wing margin in some subfamilies (e.g. Laphriinae, Asilinae), closing cell
r1. Cells m3 and cup are often closed. The abdomen
varies from cylindrical and tapering to short, broad and rather flattened; in
the Leptogastrinae the abdomen is slender, elongate and club-shaped. Acanthophorite
spines are present in females of several subfamilies and a prominent knife-like
ovipositor is formed from the terminal abdominal segments in many genera of
the Subfamily Asilinae.
Robber flies are predators
that as adults pursue other insects, seize them with powerful legs and kill them
with a paralyzing stab of the hypopharynx. The liquefied contents of the prey
are then sucked-up by the proboscis. They are mostly opportunistic predators,
feeding upon any insect that they can subdue and kill. Some species, especially
in the subfamily Laphriinae, are effective mimics of bees and wasps. Robber
flies usually hunt in open areas where there is plenty of light and warmth;
grasslands, scrub, deserts and open woodland are the best places to find them.
Larvae are predators of the eggs, larvae and pupae of other insects in the soil
(most groups) or in rotting wood (subfamily Laphriinae), although in a few
species studied the immature larvae, especially, are ectoparasitic on their
The Asilidae is a speciose
family of about 6700 described extant species worldwide. North America has 1025
named species in 97 genera; in BC 33 of these genera contain 116 species, but
it is certain that more remain to be recorded. This is 58% of the known Canadian
asilid fauna. The subfamily Leptogastrinae is represented in BC by three species
of Leptogaster. They are uncommon, extremely slender, long-legged, almost
bare flies that hover among the grasses of grasslands and dry forests in the
southern valleys. L. arida Cole is distributed from Vancouver Island
east to the dry interior of BC. Species of Dasypogoninae are distinguished by
an enlarged, or twisted spine at the apex of the fore tibia – BC has nine species
in four genera. Comantella pacifica Curran, a species known only from
grasslands in the Okanagan Valley, for a Canadian robber fly, is active unusually
late in the autumn (late October) and early in the spring (late March) indicating
that adults may overwinter in protected places. Nicocles is a genus of
beautiful flies with brown-spotted wings and, in the male, with brilliant silver
terminal abdominal segments; BC has five species. The asilids of the subfamily
Laphriinae in BC are forest dwellers whose larvae develop in rotting wood. Many
of the adults are large with colourful setulae and mimic bees and wasps. Andrenosoma
fulvicaudum (Say) is a black and orange fly that ranges across the continent
south of the northern forests. It is attracted to forest fires; the females
lay eggs in burned trees where the larvae prey on buprestid beetle larvae. Laphria contains 22 species in BC; some are bumblebee mimics with bright fuzzy yellow
and black or yellow, red and black bodies. Common Cordilleran species include L. columbica Walker and L. fernaldi (Back); L. insignis (Banks) and L. posticata Say are two of many boreal species.
The genus Cyrtopogon,
with 23 species in BC (70 in North America) is the most diverse in the Subfamily
Stenopogoninae. C. willistoni Curran is common on interior grasslands;
like some other Cyrtopogon species, the males display to females by dancing
in front of them, waving decorated tarsi. Dicolonus simplex Loew is restricted
to the Garry Oak meadows of the south coastal islands; it ranges south to California. Stenopogon inquinatus Loew, physically big and varying from red to black,
is one of the most common and conspicuous robber flies in the province; it hunts
in habitats ranging from arid sagebrush steppe to open Douglas-fir forests.
The subfamily Stichopogoninae is a small one in BC, mainly containing the genus Lasiopogon. These are small grey or brown flies that hunt from the bare
ground or from rocks and logs. L. willametti Cole and Wilcox lives on
ocean and river beaches on the south coast, L. monticola Melander is
a common species of subalpine meadows and L. quadrivittatus Jones, a
Great Plains species, inhabits the province east of the Rockies. L. hinei Cole and Wilcox is a Siberian fly that entered North America via the Bering
land bridge; it has extended its range as far east as northern BC and central
Alberta. The sole Stichopogon species in the province, S. fragilis Back, is a tiny silver fly from the sandy Okanagan grasslands at Osoyoos.
At 3 to 4 mm in length, this is BC’s smallest asilid; only a single specimen
has been collected in Canada.
In BC, the nine genera of
the subfamily Asilinae contain mostly medium-sized to large, grey or brown,
elongate flies. Efferia is the largest robber fly genus in North America
with about 110 named species; seven occur in BC grasslands. The males have large
club-shaped genitalia; the ovipositors of the females are long and sword-like.
Males of all the species have some of the abdominal segments silver-white; one
of the most common species, E. benedicti (Bromley) most of the segments
are clothed with long, white setulae parted along the midline. Megaphorus
willistoni (Cole), a rare little mimic of leaf-cutting bees, is known from
only one specimen in Canada (from the southern Similkameen Valley). The two Proctacanthus species are the largest robber flies in BC; P.
milbertii Macquart and P. occidentalis Hine are big, grey flies
reaching a length of about 40 millimetres. Rhadiurgus variabilis (Zetterstedt) is one of only two Holarctic asilid species. It is one of the most
northerly dwelling robber flies and one of the most common species in the spruce
forests of the province.
Family BOMBYLIIDAE (Bee Flies) [Fig. 39]
Members of the Bombyliidae
are called bee flies because many, in their setulation and flower-visiting habits,
resemble bees in a vague sort of way. In addition, some species develop as parasitoids
in the nests of solitary bees. Bee flies are small to large flies (1 to 25 mm
long), with the usually stout body normally clothed in delicate setulae or scales,
or both, ranging in colour from black and brown to white, silver and gold. The
wings are often patterned and colourful. The compound eyes are globular to transverse,
without setae, often meeting dorsally in males. In some groups, especially the
subfamily Anthracinae, the hind margin of the compound eye is sharply indented,
with a horizontal seam dividing the facets. There are three ocelli. The back
of the head is flat, swollen or deeply concave (e.g. subfamily Anthracinae).
The mouthparts are adapted to sucking from flowers: the proboscis is long and
slender (e.g. Subfamily Bombyliidae) or short and with fleshy labella (e.g.
subfamily Anthracinae). The antennae have 3 to 6 segments; the first segment
of the flagellum is enlarged and the others, if present, form a stylus. The
thorax is flattened or humped, with or without bristles; the latter are seldom
strongly developed. The legs are slender, with or without bristles, but normally
with bristles at the apex of the tibiae. The front legs are often thinner, shorter
and weaker than the other two pairs, especially in anthracine genera such as Exoprosopa and Poecilanthrax. The wing venation is variable. Vein
Rs normally has three branches (R2+3, R4 and R5),
with R2+3 usually ending in the wing margin toward the wing tip (and
along with R4 often bent sharply forward), but sometimes short and
joining R1. Vein M usually with two branches reaching the wing margin;
occasionally only one branch is complete because M1 ends in R5 or because M2 is absent. Cell dm is usually present and cell cup is open or closed. The abdomen is short and broad, elongate or cylindrical,
consisting of six to eight visible segments and seldom bearing bristles. The
females of many bombyliid groups have acanthophorites and spines on the tenth
segment, but many have lost these egg-laying aids. Females in advanced groups,
including the subfamilies Bombyliinae and Anthracinae, have a sand chamber,
developed through modification of segment 8, in which eggs are coated with sand
from the substrate before they are laid.
Bee flies are sun lovers
and are most diverse in hot, dry climates where sand and stony ground prevails.
They have a strong, hovering flight and usually are seen around flowers or
hovering over, or resting on, bare patches of ground. They feed on nectar and,
perhaps, some pollen from the flowers they visit. When perched, they hold their
wings outstretched and swept back. Not much is known about the development of
most species; those that have been studied are parasitoids of the immature
stages of bees, wasps, moths, beetles, flies and other insects or they prey on
the egg pods of grasshoppers. Eggs are laid near the host insects and the larvae
are similar to those of the related Nemestrinidae and Acroceridae – an active
first-instar larva seeks out the food source and moults to a grub-like form in
subsequent instars to feed voraciously on the host.
The Bombyliidae is a
speciose, worldwide family; about 4700 species are described in 230 genera.
There are 893 species in 67 genera in North America and BC has at least 50
described species shared among 17 genera. Probably the most familiar species is Bombylius major Linnaeus, a fly that ranges throughout the northern
hemisphere. Over most of the province this rotund, fuzzy fly with bicoloured
wings hums around gardens in early spring, probing flowers with its long
proboscis. The larvae are parasitic in the nests of bees such as Andrena, Colletes and Halictus. With a long proboscis and broad oval,
abdomen, Systoechus species look like BC’s approximately eight species of Bombylius; the larvae prey on grasshopper eggs. A common species is the
white or pale yellow S. oreas Osten Sacken. Anastoechus barbatus Osten Sacken, the only species of the genus in the province, also attacks
grasshopper egg-pods. Five species of the common genus Conophorus are
recorded, including C. nigripennis (Loew) and C. obesulus (Loew),
which are restricted to western North America. The Subfamily Bombyliinae in BC
also contains the distinctive genus Thevenemyia – the four BC species are
slender, black and setulose with a narrow head and prominent proboscis. They are
usually found in coniferous forests, often sitting on fallen logs. The largest, T. magnus (Osten Sacken), is about 20 mm long and has the front of the
Half the world’s described
bee flies are classified in the subfamily Anthracinae. Species of Anthrax mostly parasitize bees, wasps and tiger beetles. For example, the widespread,
speckled-winged A. irroratus Say attacks bumblebees and eumenid wasps
while A. analis (Say) feeds on various tiger beetles. The diverse genus Villa, with 52 North American species, parasitizes a wide range of flies,
moths, sawflies, bees, wasps and beetles. There are about ten BC species; the
wings are generally clear. V. alternata (Say) is named for the
alternating dark and pale bands on the abdomen; it parasitizes noctuid moth
caterpillars. Hemipenthes species have at least the basal half of the
wings heavily marked with dark brown. H. catulina Coquillett was reared
from the pupae of Bessa harveyi (Townsend), a tachinid parasite of the
larch sawfly. H. morio Linnaeus, a common Holarctic species, attacks
parasitic Hymenoptera such as Ophion. Poecilanthrax species are
big and striking, with conical faces and wings boldly marked or shaded in brown. P. tegminipennis Say is covered in yellow pile and the wings are all pale
brown; the wings of P. willistonii Coquillett are more mottled. There are
at least four species of Exoprosopa in BC; one of the more common, E.
dorcadion Osten Sacken, has wings beautifully patterned in dark
Family HILARIMORPHIDAE (Hilarimorphid Flies) [Fig. 40]
Small, dark and robust flies,
1.8 to 7.2 mm long. The head is suboval, with a concave occiput; compound eyes
bare, not emarginate laterally to the antennae. Males are holoptic, with the
compound eyes contiguous from the vertex to the base of the antennae, and with
the facets in the lower third of the compound eye smaller than those in the
upper two-thirds. Females have compound eyes small and dichoptic, with facets
of uniform size. Ocelli are present and appear prominent on a subtriangular
vertex pad, usually with several short, fine, erect setae. The antennae have
an apical 2-segmented stylus, and a short, subconical scape. The thorax dorsally
is moderately arched, and usually with distinct vittae. The scutellum is short,
relatively large, and subtriangular with short setae arranged in a row across
the posterior margin. The wings are hyaline to pale brown, covered with microtrichia,
and usually with a pterostigma. Veins are brown, with R4+5 and M1+2 similarly forked. Vein M1 is not curved forward, and vein CuA2 reaches the margin of the wing near A1. Legs are elongate, with tibiae
lacking apical spurs. Tarsal claws are simple, the pulvilli are large and distinct,
but empodia are absent. The male abdomen ends in swollen, globose terminalia,
but the abdomen in the female is gradually tapering.
Immature stages are
unknown, but adults have been collected on species of Salix growing along
narrow gravel-bottomed streams. Published BC records indicate adults are active
from mid-June to the end of July in the province.
The family contains a single,
north temperate genus Hilarimorpha. Worldwide there are approximately
30 species, seven of which occur in Canada. There are four species known from
BC: H. ditissa Webb from Pouce Coupe near Dawson Creek, H. pitans Webb collected near Chilliwack, H. rivara Webb from
near Terrace, and H. stena from Yoho National Park.
Family EMPIDIDAE (Dance Flies) [Fig. 41]
Small to medium sized,
elongate, predatory flies, 1 to 12 mm long. Usually dark coloured, but sometimes
yellowish to pale brown. Head with large compound eyes, males often holoptic,
females in the subfamily Hybotinae also holoptic; proboscis often elongate. The
antennae have 3 or fewer segments, and usually have a stylus or arista. The
thorax is usually somewhat rectangular in dorsal outline.
Wings have highly variable
venation, but the costa extends to at least the apex of the wing. Vein Sc
usually joins C or ending freely, never abruptly joining R1. Vein Rs
originates well distal to the level of crossvein h, and with vein
CuA2 usually absent or vestigial. The posterior veins in the wing are
not setose. Legs slender, usually rather long, and often exhibiting sexual
dimorphism. If sexually dimorphic, males with basal one or two tarsal segments
enlarged with silk glands. The femora may or may not be thickened, and the
middle coxae lack a strongly developed prong. The hind tarsus also has the basal
segments not expanded and flattened. The abdomen is usually more or less
elongate and cylindrical, with the terminalia in the male symmetrical or
asymmetrical, much larger than preceding segments or turned forward over these
Empidid larvae are either
aquatic or terrestrial, living in soil, leaf-litter or rotten wood. Adults are
often found on vegetation in moist habitats, on tree trunks, or on the surface
of water. Both sexes of most species feed on protein sources and nectar.
Empidids feed on live insects, especially swarming Diptera. Many species of
empidids also swarm, in spring and early summer. Males in many species present
nuptial gifts of food to females as part of the mating process. This food is
either presented to the female as captured, or may be wrapped in silk by the
male prior to presentation. Some males present a frothy "balloon" or ball of
silk to the female without any insect inside. It is thought that such silk or
silk-wrapped food, as well as insect food by itself serves to prolong the
feeding response of the female, and so distract any predaceous attack by the
female on the male.
higher classification of this group is in flux, but it is generally thought
that the Empididae, as currently defined, is a paraphyletic group with respect
to the Dolichopodidae. As the limits of monophyletic groups within the paraphyletic
Empididae are uncertain we have maintained the traditional definition of the
family which is consistent with the Manual of Nearctic Diptera. Worldwide, there
are some 4,000 described species, with about 800 reported in North America.
At least 700 species apparently occur in Canada, with at least 87 of these species
in 33 genera known from British Columbia.
Family DOLICHOPODIDAE (Long-legged Flies) [Fig. 42]
Long-legged flies are
robust, about 1 to 9 mm long, typically shining metallic green in colour, but
may be brown or black, and somewhat pruinose. Head with frons broad and narrower
anteriorly. Arista or stylus 2-segmented, dorsal or terminal on antenna. Thorax
with scutum usually strongly bristled. Wings oval in shape, with costa usually
continuous to juncture with M. Vein R not strongly thickened, but Rs arising at
or very near level of crossvein h, and R4+5 unbranched. Vein M often
straight beyond crossvein dm-cu, the cells dm and bm united. Vein A1 and cell cup sometimes rudimentary or lacking. Legs usually with large
bristles on tibiae. Male legs often highly modified, but never with one or more
of basal tarsal segments of hind tarsus expanded. Middle coxae without a prong.
Tarsi usually with bristle-like empodia and broad pulvilli. Male abdomen with
tergum 5 sometimes modified. Female with usually posterior abdominal segments
retracted into segment 5.
Most larvae are predaceous
and occur under the bark of trees, or in decaying vegetation. A few are aquatic.
Larvae pupate in a cocoon made by the larva from pieces of wood, sand or soil.
Adults are also predaceous, and are found on foliage, tree trunks, or damp
earth, usually in swamps or along partially shaded streams, where they prefer
small areas of sunlight. Males of species of Dolichopus in particular
have complex mating dances.
As noted in the discussion
of Empididae, it is generally thought that the dolichopodids form a monophyletic
group within the empidids in the broad sense. Worldwide there are over 6,600
described species in a total of over 200 described genera. Of these,
approximately 1,300 species and 57 genera occur in North America north of Mexico
and about 800 species occur in Canada. There are at least 98 described species
in 25 genera known from BC based on published records and collections of BC
Family PLATYPEZIDAE (Flat-footed Flies) [Fig. 43]
Flat-footed flies are slender
to robust, 2 to 10 mm long, black, gray, yellow, orange or brown, or a combination
of these colours, although sometimes marked with shining blue or green. Head
as broad as thorax, and rounded in front. Antennae with 3-segmented bare arista
situated terminally on flagellomere. Compound eyes of males holoptic, red, with
upper facets large and lower facets small; females with compound eyes dichoptic,
with facets small. Ocelli on prominent tubercle, especially in males. Mouthparts
short and fleshy. Thorax with transverse sutures usually visible only at the
sides. Wings clear or brownish, the veins in the posterior half of the wing
not setose. Vein C extending to at least apex of wing; subcosta reaching wing
margin; radial veins not strongly thickened. Characteristically, the wings of
platypezids have a relatively large cup cell which always ends in an
acute angle. Legs stout and with middle coxae lacking a prong. Often the hind
tarsus of males, and in some genera also the females, are expanded or dilated,
often appearing as flattened plates in dried specimens. The abdomen is elongate;
and cylindrical or somewhat flattened.
Larvae of all flat-footed
flies appear to feed in damp woods (on fungi), where the adults are often
encountered running erratically in a zigzag, stop-and-go, fashion on leaves of
bushes in filtered sunlight, likely feeding on honeydew and other deposits on
the leaves. Adults may also be seen hovering or running across the damp sand of
stream beds. Males can form aerial swarms, into which females enter to select
mates. Adults of Microsania are attracted to smoke; Microsania
occidentalis Malloch is a widespread western species in this genus that
likely occurs in BC.
Worldwide there are about
20 described genera and 250 described species. Sixteen genera and 74 described
species occur in North America, of these, nine genera and 16 species are known
from BC collections.
Family LONCHOPTERIDAE (Pointed-wing Flies or spear-winged flies)
Pointed–wing or spear-winged
flies are small and slender, yellowish to brown flies, 2 to 4 mm long. The head
is as wide as or wider than the thorax. The compound eyes are broadly separated
in both sexes. The frons is short and broad, and bare except for a pair of strong
and divergent lower interfrontal bristles medially above antennae. Antennae
short, with bases widely separated, and with all segments small. Scape and pedicel
each with a row of short bristles on the distal margin. The antennal arista
is exposed, arises apically and has a short pubescence. The compound eyes are
moderately large, bare, and prominent; the ocelli are small and equidistant
from each other. The proboscis is short, with palps short and clavate. The thorax
is subrectangular, and convex dorsally. The scutum is rather strongly arched
anteriorly, and the scutellum is moderately large, triangular, and rounded posteriorly.
The legs are large and slender, with claws and pulvilli small, but the empodia
are evidently absent. The hind femora are slightly swollen, and the fore tarsi
of the male are also slightly swollen. The wings are elongate, slender, and
somewhat pointed apically, with linear venation which shows sexual dimorphism.
The main veins except Sc and R3 have black setulae on the dorsal
surface, vein M is branched, and the crossvein r-m is situated near the base
of the wing well before the middle of the wing. Vein CuA2 does not
reach the wing margin as a free vein, but in the male terminates as A1+CuA2.
In the female it terminates as A2+CuA2+CuA1.
The abdomen is rather short, subcylindrical to oval.
Larvae live under leaves
or in decaying vegetation, probably feeding in micro-organisms and fungal
hyphae. Adults are found in moist, shady habitats, and have a characteristic
The family contains a single
genus, Lonchoptera, with four Nearctic species , all of which occur in
Canada. There are 35 described species worldwide. Lonchoptera bi
(Fallén) occurs worldwide
and has both a bisexual and a parthenogenetic form. Besides L. bifurcata, Lonchoptera borealis Curran and Lonchoptera uniseta Curran are known to occur in BC.
Family PHORIDAE (Phorid Flies) [Fig. 45]
Minute to small, inconspicuous,
blackish, brownish or yellowish flies, 0.5 to 6.0 mm long, with major bristles
on head, legs and other parts of the body characteristically feathered. The
head is small, sometimes rather short and flattened, with ocelli present except
in apterous forms. The thorax has a characteristic hump-backed appearance. Legs
are well developed with the hind femur often enlarged, and more or less laterally
compressed. The tibiae have one or more apical bristles, with one or more seams
often on the hind, and sometimes also on the middle tibia. The wings are usually
large, usually hyaline to pale brown, and rarely with dark markings, but females
are sometimes short-winged or apterous. Fully developed wings have the branches
of R strongly thickened and crowded into the antero-basal portion of wing, but
with four other weak and peculiarly defined veins in the remainder of the wing
blade. The costa ends near the middle of the anterior margin of the wing, and
the veins in the posterior half of the wing are not setose. The abdomen is somewhat
conical, and more or less tapering posteriorly, but often it is membranous,
especially in wingless forms.
Adults move about with a
characteristic quick, jerky movement. They are common around decaying vegetation
or animal matter, and sometimes in and around the nest of ants, termites and
Larval habits are varied,
with many having been reared from fleshy or woody fungi. Some are scavengers,
and some are parasites. The parasitic forms are often found in the nest of ants,
termites, bees and wasps, and on beetles, caterpillars, millipedes and land
Worldwide there are about
245 described genera and over 3000 described species. There are over 50 genera
and about 380 described species in the Nearctic; of these there are at least 50
described species in 18 genera known from BC based on published records and
collections of BC flies.
Family SYRPHIDAE (Flower Flies) [Fig. 46]
Slender to robust flies, 4
to 25 mm long, with body usually black and strikingly marked with yellow or
orange on the head, thorax and abdomen. Many such species are mimics of bees and
wasps. Less commonly, species are brown, yellow or metallic green or blue, or
with various combination of such colour. The integument is usually smooth, but
sometimes is totally or partly punctate, sculptured or rugose, and may be
somewhat pruinose. The body is usually covered with dense, short setae, but
rarely may be almost bare, or with long setae or stout bristles. The setae are
sometimes flattened or scale-like, forming a dense tomentum. The compound eyes
are usually holoptic in males, but can be very narrowly or broadly dichoptic.
Females are moderately to broadly dichoptic. Some or all of the facets in the
upper part of the compound eye may be enlarged in the male. However, the eyes
are usually unicolourous, but rarely can have dark spots or bands, or have
irregular markings, and may be bare or setose, with short or long, sparse or
dense, setae. Three ocelli are present, and the antennae are sometimes set on a
short or long frontal prominence. The lower facial margin usually has a distinct
median notch. The arrangement of thoracic bristles or setae is important
taxonomically. The wings are usually hyaline, but sometimes are somewhat
darkened or with distinct markings. Characteristically, theses flies have the
costa ending at the apex of R4+5, and there is an unattached
longitudinal vein, the spurious vein (vena spurea), running most of the
length of cells br and r4+5, posterior to Rs. The apex of vein M is
bent strongly forward near the wing margin, and joins near the end of
R4+5, thus forming an apical crossvein. Cell cup in the wing
is closed near the wing margin, and a pterostigma is usually present. The legs
are usually slender, but can be somewhat modified, especially in males. The
abdomen is usually suboval, but can be elongate or even petiolate.
Adults of the subfamilies
Syrphinae and Eristalinae are habitual visitors of flowers for obtaining pollen,
nectar and honeydew, and are important pollinators: they are often considered
second only in importance to some bee species in cross-pollinating many economic
plants. Males are often seen hovering, almost motionless in the air, but dart
swiftly aside when disturbed.
Adults lay oval,
chalky-white, sculptured eggs on or near the food of the larvae, those with
aphidophagous larvae being laid singly, but others may lay eggs in masses of
over 100. Larvae have a wide variety of habitats and food. Some are predaceous
(Syrphinae, Pipizini), but others are phytophagous (Cheilosia,
Merodontini), saprophagous (most Eristalinae), or scavengers (Volucella,
Microdontinae). The mouth parts of such larvae are thus quite different.
Predaceous types have four stylets for piercing and sucking, while phytophagous
forms have strong mandibles. Saphrophagous species have a complex comb-like
mandibular lobe, and like the scavengers, have a muscular and contractile
The predaceous larvae of
the Syrphinae feed primarily on aphids and other Homoptera, but some species
have been reported to feed on immature thrips, beetle, or lepidopterous larvae.
Larvae of the Pipizini feed on aphids, preferring woolly or root aphids with a
waxy integument, and attack these living both above and below ground. Larvae of
the Syrphinae and Pipizini are thus important in natural biological control. The
phytophagous larvae of Cheilosia feed in fungi or vascular plants, while
the larvae of the Merodontini live in monocotyledonous bulbs, and sometimes in
other plants, and may cause considerable economic damage.
The saprophagous larvae of
most species of Eristalinae live in tree holes, ulcerated tree wounds, or
rotting wood, but larvae of species of the tribes Eristalini and Sericomyiini
are aquatic, living in water with a high organic content. The larvae of the
Eristalini are the rat-tailed maggots, so called because the end of the abdomen
is drawn out into a protrusible rat-tail-like respiratory siphon. Among the
scavengers, the larvae of the Microdontinae are known to live only in ant nests,
and the larvae of Volucella likewise are scavengers in nests of colonial
One of the most common
syrphids in British Columbia is the cosmopolitan Eristalis tenax (Linnaeus). Although larvae of this species are aquatic, they have also been
found living in the urogenital opening of cows. Three species of Syrphinae,
namely Eupeodes perplexus (Osburn), E. venablesi (Curran) and Syrphus opinator Osten Sacken have been reported as important predators
in the natural control of the woolly aphid Eriosoma langerum (Hausmann)
in British Columbia. The Narcissus bulb fly. Merodon equestris (Fabricius), is a pest of Narcissus and other bulbs, and most years
causes considerable loss to some bulb growers. Larvae of Heilosia are
called bark maggots, and cause a blemish in timber of western hemlock and other
conifers, known in the lumber industry as "black check".
Worldwide there are some
180 recognized genera, and about 6000 species. In the Nearctic there are 87
described genera, and about 900 described species. Some 550 species are reported
from Canada, with the Syrphinae monographed by Vockeroth (1992).
Vockeroth, J.R. 1992. The
flower flies of the subfamily Syrphinae of Canada, Alaska, and Greenland.
Diptera: Syrphidae. The Insects and Arachnids of Canada. Part 18. Research
Branch Agriculture Canada Publ. 1867:456 pp.
Family PIPUNCULIDAE (Big-headed or Big-eyed Flies) [Fig. 47]
Big-headed flies are
small, dark bodied, 3 to 15 mm long, with characteristic globose or semiglobose
compound eyes, covering almost the entire head. The compound eyes of males are
usually contiguous in front, but dichoptic in the subfamily Chalarinae. The
occiput is very narrow in the Chalarinae, and has ocellar bristles. In the
Pipunculinae the occiput is generally swollen, clearly visible and lacks ocellar
bristles. The thorax is shiny black, and pruinose to a varying degree, but
usually somewhat setose. The femora of the legs usually have rows of small
spines ventrally towards the apex. The hind tibiae often have strongly, erect
anterior setae medially. The claws and pulvilli are moderately large. The wings
are typically long and slender, hyaline to faintly infuscate, and iridescent in
direct light. The costa ends at the wing apex, and R4+5 is
unbranched. The abdomen is typically subcylindrical.
Adults are frequently
found hovering in or over vegetation. Females search out immature leafhoppers
and other Homoptera for ovipositon. Females snatch the prey with their long legs
and hold them in their strong tarsal claws. While in flight, females then insert
an egg into the host through weak areas of the abdomen. The larvae are
endoparasitic, and develop to maturity in the host. They then emerge, drop to
the ground and pupate in the soil or ground litter.
Worldwide there are about
1, 380 described species. In the Nearctic there are 12 to 14 described genera
(depending on generic definitions) with about 175 described species; of these,
nine genera and 35 described species are known from BC based on published
records and collections of BC flies.
(Thick-headed Flies) [Fig. 58]
Thick-headed flies are small to medium sized (3 to 20 mm
long), usually rather elongate, wasp-like and lacking prominent setae or bristles.
They are coloured black and yellow, black, or red-brown, frequently with pruinescence;
the wings are often spotted or darkened along the front margin. The head is
large, broader than the thorax; the bare compound eyes are widely separated
in both sexes. Ocelli are absent in the Subfamily Conopinae, but are present
in other groups. The proboscis is long, elbowed at the base (Conopinae and the
genus Zodion) or elbowed at both the base and in the middle of the proboscis.
The antennae are variable: the first segment of the flagellum is elongate with
a short 3-segmented stylus (Conopinae) or is short, bearing a 2- or 3-segmented
arista on the upper surface. Wing with R4+5 and M1+2 strongly
convergent and sometimes fused near the wing tip, closing cell R4+5.
A short crossvein joins Sc and R near the end of Sc in some genera. Sometimes
a spurious vein occurs, running outwards from crossvein r-m. Cell cup is
always closed and petiolate. The legs are almost bare and lack distinct bristles;
they are rather uniform, although the femora are thickened in some genera. The
abdomen is cylindrical and more or less club-shaped, broad or constricted at
the base and often curving downward at the tip. In the female, the sterna of
segment 5 and/or 6 are often enlarged and plate-like.
Adult conopids are
frequently wasp-like in form and colour and apparently mimic various
Hymenoptera. They are notorious for their variability, especially in coloration.
They feed at flowers, especially of the aster, mint and carrot families. The
known larvae of most genera (and all those found in BC) are internal parasitoids
of aculeate Hymenoptera. Adult females deposit eggs on the hosts in flight. The
Subfamily Stylogasterinae, species of which are not known to occur in BC,
parasitize cockroaches and calyptrate Diptera; females are known to hover over
the front lines of army ant columns laying eggs as their hosts are flushed by
The Family Conopidae is
small, with about 800 described species in 45 genera, but it is widespread over
much of the Earth. In North America there are nine genera and 67 species
described; many species range across the whole continent. BC has six genera and
24 described species. Perhaps the most readily seen genus in the province is Physocephalus, with its three rather large, red-brown species. P.
burgessi (Williston) ranges across southern BC; and south to Texas and
California; it attacks bumblebees such as Bombus pennsylvanicus (Degeer). Physocephalus marginata (Say) and P. texana (Williston) are transcontinental; the former is a known parasite of honeybees
and latter has been found in the nests of the digger wasp, Bembix americana Fabricius and the bumblebee, Bombus terricola Kirby. Physoconops
obscuripennis (Williston) is waspish, yellow and black, and about 1 cm long;
it is known from the Thompson-Okanagan region. Dalmannia picta Williston,
also yellow and black and from the Interior, is smaller. About six species of Myopa are known in BC; M. rubida (Bigot) is one of the more common
ones, ranging south to Colorado and California. One of its hosts is the bee
genus Andrena. Zodion americanum Wiedemann is a tiny (3.5 mm long)
conopid distributed from sea to sea and south into southern South America. At
least five other species in the genus live in BC; Z. fulvifrons Say,
sometimes a parasite of honeybees, is known from the dry Interior. The six
species of Thecophora recorded in BC are usually black and rather small,
averaging 5mm long; T. longicornis (Say) ranges over most of North
Smith, K.G.V. 1959. The
Conopidae (Diptera) of British Columbia. Proceedings of the Entomological
Society of British Columbia 56: 54-56.
Family LONCHAEIDAE (Lance Flies) [Fig. 59]
Lance flies are stout, setose,
3 to 6 mm long, with a large, wide head and a broad, flattened abdomen. The
body is usually shining blue-black, sometimes dull brown; normally, the wings
are clear, but often clouded with yellow or brown. The halter is black. In lateral
view the compound eyes are large and round to oval. The frons is setulose, narrower
in male than in female; the lunule is large and exposed. One orbital bristle,
one inner and one outer vertical bristle are present, and ocellar bristles are
strong. No vibrissae are present, but some subvibrissal setae may be enlarged.
Antenna with the third segment short or long and narrow, black to orange, often
hanging vertically; the arista is bare, pubescent or plumose. Thorax with scutum
arched, black or brown and pruinose to shining; the setulae and bristles are
usually dense and strong. The scutellum has two pairs of bristles, one apical
and one basal. The wing is normally strongly tapered from base to tip; C extends
to M and is constricted or broken at the end of Sc; Sc is complete. Vein A1 is short or continues toward wing margin as a sinuate fold. The upper calypter
is prominent, with white to brown margins. The legs are stout and black; the
tarsi are often yellow. The femora often are strongly setose and bristled; the
mid tibiae bear a bristle underneath at the tip.
Lance flies are commonly
secondary invaders of injured or decaying vegetation. Larvae of Lonchaea and Dasiops often live under the bark of dead or dying trees (mainly
conifers) or in damaged or rotting fruits and vegetables. Some are associated
with plant-attacking insects such as bark beetles, weevils and fruit flies,
where they scavange or prey on larvae. Others may be primary invaders of plants;
for example, most species of Earomyia infest the cones of conifer trees.
Male adults of some species swarm in patches of light in woodland.
The Family Lonchaeidae contains
ten genera and about 700 described species. There are six genera and about 120
named species in North America. In all, the province has about 44 species in
five genera. Lonchaea is the most speciose genus, with about 70 Nearctic
species; at least 31 of these live in BC. Lonchaea chorea (Fabricius), L. flavipennis Morge, L. laxa Collin and L. zetterstedti Becker are Holarctic; they range across the North American boreal forest. The
latter preys on bark beetles in European conifers – it is widespread in BC and
probably feeds on beetles in spruce trees. Some BC species restricted to the
west include L. atritarsus Malloch, L. foxleei McAlpine, and L.
ursina Malloch. Four species of Earomyia are recorded in BC, E.
aquilonia McAlpine and E. abietum McAlpine are common; the former
feeds in the cones of Subalpine Fir and Douglas Fir, the latter on Amabilis
and Grand Fir. At least six Dasiops species live in BC. Dasiops albiceps (Malloch) is boreal; D. obscurus (Coquillett) is a western species. Also
western in range is Chaetolonchaea americana McAlpine, the only species
in the genus restricted to North America. Protearomyia cordillerensis McAlpine is a species of the western mountains and P. trichopleura McAlpine
Family PALLOPTERIDAE (Flutter Flies) [Fig. 60]
Flutter flies are small to medium-sized (3 to 5 mm long),
with grey or yellow bodies and brown-patterned wings. The head is higher than
long with the frons broader than high and always yellow, at least on the front
half. One pair of orbital bristles and strong ocellar and inner and outer vertical
bristles present. The pair of post ocellar bristles is weaker and somewhat divergent.
The yellow face is slightly convex, usually with a median ridge and lacks setae.
There are no oral vibrissae. The small antenna has the second segment notched
at the tip and bears a single bristle; the third segment is oval with a bare
or short-setulose arista. The thorax is yellow to black and normally pruinose,
but sometimes shining or patterned in yellow and black; thoracic bristles are
prominent. The wing is rather long and narrow, usually with brown markings.
Subcosta is complete; cell sc is always dark. The costa has three weakenings
or breaks and ends just beyond its junction with R4+5. Cell cup is convex at the tip; vein A1 reaches or almost reaches the wing
margin, at least as a fold. Tibiae and tarsi are usually yellow; the tibiae
lack preapical dorsal bristles, but the middle tibia has an apicoventral bristle.
The abdomen is elongate oval, yellow to dark brown and normally unpatterned.
Flutter fly larvae are apparently
phytophagous or carnivorous. Some have been found in the flower buds and stems
of plants in the aster and carrot families. Others live under the bark of dead
trees and prey on the larvae of long-horned and bark beetles. On Vancouver Island, Palloptera claripennis Malloch, has been reared from the cones of Douglas-fir,
where the larvae fed on the larvae of Contarinia midges (Cecidomyiidae).
Adults are usually seen on flowers or on the lower branches of trees and shrubs.
Males vibrate their wings, giving the family its English name -- flutter flies.
The Pallopteridae is a
small family, closely related to the Piophilidae and distributed in the north
temperate region, temperate South America and New Zealand. Worldwide there are
about 54 described extant species in 12 genera. All nine described North
American species are now placed in the genus Palloptera; at least six of
these live in BC. P. claripennis Malloch, P. albertensis Johnson, P. subusta Malloch and P. terminalis Loew range in the western
mountains and valleys; P. jucunda Loew and P. subarcuata Johnson
are transcontinental. There are several additional species in BC awaiting formal
Family PIOPHILIDAE (Skipper Flies) [Fig. 61]
Skipper flies are small
(3 to 6 mm long) and vary in colour from metallic black or blue-black to pale
brown or yellow. The head between the compound eyes, especially in front, is
often yellow. Bristles are usually strong and black and the body is sometimes
densely setulose. The wings are usually clear and iridescent, but some genera
(eg, Mycetaulus) have brown-marked wings. Viewed from the side, the head
is normally higher than long; the compound eyes are nearly round and lack setulae.
The frons is parallel-sided, as broad as long in both sexes. There are two or
three orbital bristles, the inner and outer vertical bristles are about the
same size, the two ocellar bristles point forward and the postocellar bristles
diverge. The oral vibrissae are usually prominent -- sometimes there are several
and in Amphipogon they form a thick beard. The face is convex, with the
antennae seated in grooves. The second antennal segment lacks a dorsal seam,
but normally bears a dorsal bristle; the segment is about as long as wide, but
is strikingly elongate in males of Prochyliza xanthostoma Walker. The
third segment is oval with a bare or short-setulose arista arising near the
base. The scutum normally is shiny, but is pruinose in some Mycetaulus;
it is densely setulose to almost bare. The scutellum is sometimes flattened
and occasionally bears a pair of tubercles; there are four bristles. In the
wing, the costa has a subcostal break; all veins lack setae in BC species. Subcosta
is complete and not fused with R; vein A1 faintly reaches the wing
margin or ends abruptly just before the edge. The tibiae lack preapical dorsal
bristles, but often have other strong bristles, especially ventrally and laterally
near the tip. The abdomen is shiny black to yellow and lacks a colour pattern.
Skipper flies usually
develop in dead animal matter (especially dried carcasses advanced in decay) and
rotting fungi. The larvae of one European species are ectoparasitic blood
feeders on passerine bird nestlings. Perhaps the best-known species, Piophila
casei (Linnaeus) (Cheese Skipper) infests cheeses, meats and hides and can
be a serious pest in the food industry. This fly has also caused mild nasal and
enteric myiasis when people have eaten maggot-infested cheese. The larvae are
called skippers because they can flip into the air like little
The Family Piophilidae
contains 69 described species in 23 genera world wide, but is most diverse in
the northern temperate regions. Over forty described North American species are
placed in 14 genera, 11 of which contain Holarctic species. There are nine
genera known in BC, all of which have Holarctic members, and at least 29 species
including several that are awaiting formal scientific description. Described BC
species include the cosmopolitan Piophila casei (Linnaeus), a pest of
stored cheese and meat. Actenoptera hilarella (Zetterstedt) is Holarctic
and, in North America, ranges transcontinentally; it is known from Vancouver
Island. Allopiophila testacea Melander ranges across the western
provinces; the bizarrely bearded Amphipogon hyperboreus (Green) is a
boreal species. It develops in fungi, as do species of Mycetaulus such as M. bipunctata (Fallén), M. nigritellus Melander and M.
polypori Melander. Parapiophila species are mostly shining black; P atrifrons (Melander and Spuler) and P. xanthopoda (Melander and
Spuler) are western species known from the BC Interior. Parapiophila
vulgaris (Fallén), a Holarctic fly, has been found on the outer coast of
Vancouver Island as has Liopiophila varipes Meigen, which, similarly, is
transcontinental and Holarctic in distribution. Prochyliza contains at
least four species in BC; P. xanthostoma Walker ranges across the
continent and can be common around garbage. P. brevicornis Melander has
been found on vertebrate cadavers. Stearibia nigriceps Meigen is
(Picture-winged Flies) [Fig. 62]
The family Otitidae contains small to medium-sized flies
(North American species are 3 to 12 mm long); the body is often brightly
coloured and frequently metallic. The wings are banded or patterned with black,
brown or yellow. The head in profile is normally higher than long; inner and
outer vertical bristles, ocellar, postocellar and one or two orbital bristles
usually present. Vibrissae are absent. The face is normally fully sclerotized,
broad and convex. The size and shape of the antenna is variable; the third
segment often has a sharp tip and the arista is long and bare to plumose. The
wing has Sc complete, its tip gently curved; R1 is bare or setulose.
Cell cup usually has an acute projection at the postero-distal corner.
Female has abdominal segment 7 flattened and more or less triangular; the
ovipositor is sword-like.
The larvae of
picture-winged flies live in decaying vegetable refuse and other organic
material such as dung. Some feed under the bark of dead trees and others are
phytophagous; a few, such as those attacking sugar beets and onions, are
economically important. Adults can be common in moist places and meadows; they
rest on low vegetation and visit flowers, fungi and tree wounds. Many vibrate
their patterned wings during mating displays.
The family Otitidae
consists of two subfamilies, the Otitinae and Ulidiinae, which are sometimes
considered separate families. The family consists of about 800 described species
in 50 genera of which 41 genera and 133 described species occur in North
America. There are at least 15 genera and 23 species known from the published
literature and collections of BC Diptera. The Ulidiinae is widespread in the
tropics; in BC it contains the genera Homalocephala and Physiphora. The former genus contains four species in North America, all
in the boreal or mountain forests; at least three, H. albitarsis Zetterstedt, H. apicalis (Wahlberg) and H. similis (Cresson) are
recorded in BC; the larvae are found in conifers such as pines. Physiphora contains two common scavenging flies, originally from Europe and
now cosmopolitan -- P. demandata (Fabricius) develops in livestock dung
in southern BC; P. aenea (Fabricius) also probably occurs in the
province. The Otitinae is more diverse. Ceroxys latiuscula (Loew), the
sole Nearctic species in its genus, is western, but has emigrated as far as
Hawaii and Samoa. Curranops apicalis (Cole) ranges from BC to California. Herina canadensis (Johnson) is transcontinental; H. nigribasis McAlpine is western. Melieria, with barred and spotted wings, has four
species in BC; one, M. cana (Loew), is Holarctic. Seioptera
vibrans (Linnaeus) is Holarctic; the lavae feed on decaying potatoes and
onions. Tetanops myopaeformis (Röder) is a pest of sugar beets in the
West. Other BC genera include Otites, Pseudotephritis, Psaeropterella and Tritoxa.
Family PLATYSTOMATIDAE (Platystomatid flies) [Fig. 63]
Platystomatids are small to medium-sized flies (3 to 12
mm long), with bodies often brightly metallic and wings usually strongly banded.
The head is higher than long, with the number of bristles reduced; there are
one or two orbital bristles, an inner and outer vertical bristle and a single
genal bristle. The third antennal segment is usually elongate, sometimes with
a sharp point at the tip, and bearing a slender arista, either bare or setose.
The proboscis and palps
are well developed. Thorax with at most one pair of dorsocentral bristles; two
or three pairs of scutellar bristles present. The wing is normally long and
slender; C with break near base, but no subcostal break near end of Sc. Vein Sc
is complete; vein R1 is setose above. Cell cup is always rounded at the
tip, never with a pointed extension at the lower end.
Little is known of the
life histories of platystomatid flies, but the lives of adults and larvae are
probably much like those of the Otitidae. In other parts of the world, adults
frequently visit mammal dung; larvae live in logs and vegetation damaged by
other insects or attacked by fungi.
Closely related to the Otitidae
(and in the past classified as a subfamily within it), most of the 119 genera
and 1200 described species of Platystomatidae are found in tropical and subtropical
Africa, Asia and Australia. North America records 41 species in four genera,
by far the largest being the world-wide genus Rivellia. Two platystomatid
species are known in BC. R. maculosa Namba ranges from the southern Alberta
Rocky Mountains east to North Carolina and Florida and is likely to be found
in BC. Senopterina foxleei Shewell lives from BC to the US Southeast.
Other species, yet to be recorded, probably occur in the province.
Family TEPHRITIDAE (Fruit Flies) [Fig. 64]
Small to medium-sized and often brightly coloured,
tephritid flies usually have wings banded or spotted in various patterns. The
head is variable; in some exotic species the compound eyes are stalked. Usually
one pair of inner and outer vertical bristles occur, along with one pair of
postocellars and ocellars and one to several pairs of orbital and frontal
bristles. The latter two types of setae are sometimes thickened or flattened.
Vibrissae are absent. The second antennal segment sometimes bears a seam on top
and the third segment is often pointed on the upper end; the arista is usually
bare or finely setulose. The proboscis is sometimes long and elbowed. The
scutellum is swollen and shining in some genera, with 1-4 pairs of bristles,
normally on the margin. The bristles on the scutum are variable, but there is
always at least one pair each of dorsocentral and acrostichal bristles. The wing
has a distinctive Sc bent sharply forward toward the costa and weakened after
the bend, often not reaching the costa. Vein R1 always bears short
setae above. The cell cup usually has an acute projection on the hind
margin. Colour patterns usually present, ranging from almost entirely dark brown
or black to combinations of bands, stripes, spots or reticulations in black,
browns and yellows.
Adult female fruit flies
lay eggs in living, healthy plant tissue and the developing maggots feed in a
wide variety of plant parts, depending on the species. Some form galls on stems
and roots; a few tunnel in leaves; others develop in the fruits, seeds and
ovaries, especially in plants of the huge aster family. Those that attack fruits
and vegetables can be severe agricultural pests. One of the worst, Ceratitis
capitata (Wiedemann) (Mediterranean Fruit Fly) does not occur in BC. The
Tephritidae is among the most economically important fly families, not only
because of its destruction of useful plants, but also because many species are
extensively used in the biological control of weeds. Adults are frequently seen
on their host plants, walking around and raising and lowering their patterned
The Family Tephritidae
is a speciose cosmopolitan family of about 4350 known species, in 481 genera;
62 genera and about 361 species are known in the Nearctic. In BC there are at
least 70 species in 24 genera based on the published literature and collections
of BC Diptera. The genus Rhagoletis is important economically; many of
the species attack agricultural crops. Adults are usually dark bodied, with
the wing marked with three more or less transverse bands, the outer one extending
along the front of the wing apex. Rhagoletis indifferens Curran (Western
Cherry Fruit Fly) first appeared in Okanagan cherry orchards in 1968. Its principal
host is the native Prunus emarginata Douglas; R. fausta (Osten
Sacken) (Black cherry Fruit Fly) is much less common. In 2006 R. pomonella (Walsh) (Apple Maggot) first appeared in BC in the Fraser Valley and southern
Vancouver Island after spreading over much of North America in the last 100
years. It is native to the eastern US and apparently transferred from wild hawthorns
and crabapples to commercial apple crops there in the 1870s. So far, this important
pest has not appeared in BC's Okanagan Valley, the only major North American
apple growing area where it has not been detected. R. basiola (Osten
Sacken) is widespread on wild roses, R. berberis Curran attacks Oregon
Grape and R. ribicola Doane feeds on currants. R. tabellaria (Fitch)
develops in currants and juniper berries, R. zephyria Snow in snowberries
(Symphoricarpos). Euphranta canadensis (Loew) attacks gooseberries and
currants all over North America; it is yellow with green eyes and narrow bands
on the wings.
Many of BC’s fruit flies
breed in flower heads, especially in plants of the Family Asteraceae; Trupanea
californica Malloch and Campiglossa variabilis (Doane), from the
valleys of the southern Interior, are examples. Others include C. genalis (Thomson), developing in Senecio and other genera, C. murina (Doane)
in Chrysothamnus nauseosus (Rabbitbrush), Euaresta aequalis (Loew)
in Xanthium strumarium (Common Cocklebur), Tephritis angustipennis (Loew) in Achillea millefolium (Yarrow), T. araneosa (Coquillett)
in Artemisia (sages) and Arnica and Terellia occidentalis (Snow) and T. ruficauda (Fabricius) in Cirsium (thistles). Urophora
affinis Frauenfeld and U. quadrifasciata (Meigen) were introduced
from Eurasia into the grasslands of the southern Interior to combat the noxious Centaurea diffusa (Diffuse Knapweed) and other knapweeds. Together they
have reduced seed production of diffuse knapweed by 86 %. Eurosta species
have broad wings speckled with yellow; they make root and stem galls. E.
solidaginis (Fitch) makes globular galls on the stems of goldenrod plants. Eutreta diana (Osten Sacken), with a bright rufous abdomen and brown
wings with clear spots, produces galls on Artemisia tridentata (Big Sagebrush).
PYRGOTIDAE (Pyrgotid Flies) [Fig. 65]
Pyrgotids are medium to
large flies (wings 6-18 mm long), relatively slender, usually with strongly
patterned wings. Head is usually prominent and rounded although sometimes
tapering ventrally; face often broad with a medial pronounced ridge. Mouthparts,
palpi, and compound eyes normal; vibrissae and ocelli absent. Head bristling
often greatly reduced with the exception of the inner vertical bristle which is
always distinct, ocellar and postocellar setae sometimes well-developed (BC
species). Antenna generally large, with an elongate pedicel; flagellomere
somewhat oval in shape, with a medial to near basal, bare arista. Dorsal
thoracic bristles generally reduced giving thorax a setulose
Wing long, with a humeral
break and sometimes a subcostal break in the costa; subcosta usually reaching
costa. Wing with either a distinct banding pattern, like some Tephritidae, or
with a more diffuse mottled colouring. Cell dm long, cell cup with lower
apical corner straight (1 North American species) to having a long pointed corner
(most species including the BC species). Alula and calypteres well developed
(BC species) to virtually absent. Legs long, but robust; strong bristles lacking;
hind tibia of BC species with basal third much smaller in diameter than apical
two-thirds. The abdomen of the female is greatly elongate and highly modified
to lay eggs onto adult scarab beetles while in flight. Larval pyrgotids are
internal parasites of adult scarabs and some pyrgotid species are known to help
control population levels of some species of pest scarabs. As the scarabs fly
at night, generally it is most effective to collect pyrgotids at night using
light traps when the flies are actively pursuing hosts.
There are about 330
described species in 50 genera worldwide, with 8 species in 5 genera occurring
in North America, north of Mexico. These species were reviewed by Steyskal
(1978) who noted that there is only one species known from BC. Boreothrinax
shewelli Steyskal has been collected from Oliver, Keremeos and Victoria
during the month of April and from Boulder Colorado in May; its host is
Steyskal, G.C. 1978.
Synopsis of the North American Pyrgotidae (Diptera). Proceedings of the
Entomological Society of Washington 80: 149-155.
Family MICROPEZIDAE (Stilt-legged Flies) [Fig. 66]
Stilt-legged flies are small
to medium-sized (3.5 to 20 mm long), slender, and almost without bristles or
setulae. The common name, stilt-legged flies, is a reference to the strikingly
long, slender legs. Colours vary from yellow through red to black and the body
often is banded or has pale pruinescence. The wings are clear or coloured, often
with spots or bands of brown. The head is usually globular or sometimes conical
and pointed in front (eg, Micropeza). The eyes are large. The third segment
of the antenna is oval and, on top near its base it bears a setose or bare arista.
There are no vibrissae or ocellar bristles. The thorax is elongate, with the
front legs placed well forward of the middle pair; the scutellum is small with
one pair of bristles. The wing is long and slender. Vein C reaches the wing
tip at vein M1+2 and has no breaks; Sc is complete. All longitudinal
veins are rather straight and extend to the wing margin; R4+5 and
M1+2 usually converge or fuse near wing tip. Cell dm is long and
narrow. The abdomen is elongate, slender and sometimes constricted at the base;
the genitalia of both sexes are flexed down and forward. Males often have processes
under segments 5 and 6 and laterally on segment 7 (especially on left side).
Stilt-legged fly larvae
develop in decaying wood, fruit and other vegetable matter. Some larvae feed in
dung and one oriental species attacks growing ginger roots. Adults are usually
found in marshes or wet woods, perched on leaves and tree trunks, often at
wounds in the bark. Some are evidently predators of aphids and other small
insects that they stalk in vegetation. Still others are wingless and mimic
The Micropezidae is a cosmopolitan,
but mainly tropical family containing about 520 described species, 33 of which
are known from North America. Three genera and nine species are recorded in
BC. The genus Micropeza has 16 of these species, but only M. lineata Van Duzee, a widespread western species and M. chillcotti Merritt and
Peterson, known only from Vancouver, are known in BC. Cnodacophora nasoni (Cresson) ranges across the boreal and mountain forests, south in the west to
Colorado and in the east to New York. There are at least six species of Compsobata in the province. C. univitta (Walker) is a red fly with a pruinose
thorax; it is distributed transcontinentally. C. mima (Hennig) and C.
pallipes (Say) are black with the thorax partly shining above; the former
is western, the latter is transcontinental. C. columbiana Merritt and
Peterson, is one of BC’s most common and widespread micropezids. In BC, C.
jamesi Merritt is restricted to the south coast and C. kennicotti has been recorded only near the Yukon border.
Merritt, R.W. and B.V.
Peterson. 1976. A synopsis of the Micropezidae (Diptera) of Canada and Alaska,
with descriptions of four new species. Canadian Journal of Zoology 54:
Family TANYPEZIDAE (Tanypezid Flies) [Fig. 67]
North American tanypezids
are 5 to 7 mm long, slender, long-legged and with patches of silvery tomentum
on the body. The legs are yellow. The head, in profile, is higher than long;
the compound eyes are very large. The frons is narrower than the eye and is
much narrower in males than in females. The third antennal segment is oval,
rather large and somewhat elongate, with a basal, setulose arista. Vibrissae
are absent; the upper orbital bristle arises on the vertex. The scutellum has
two pairs of bristles, but is otherwise bare. The wing is clear; the costa has
a weak subcostal break and Sc is complete. Veins R4+5 and M almost
meet at the wing tip; cell cup is closed by the L-shaped CuA2. Vein
A1 almost reaches the wing margin.
Hardly anything is known
of the biology of the family. The adults live in damp forests.
The Tanypezidae is primarily
a New World family containing three genera and about 22 species. Only Tanypeza, with two species, occurs in North America. T. longimana Fallén is
Holarctic and in the Nearctic ranges from the Rocky Mountains to the Atlantic
Ocean. T. picticornis Knab and Shannon has an eastern North American
distribution. Although T. longimana Fallén is not recorded in BC, it
likely occurs throughout the province.
(Strongylopthalmyiid Flies) [Fig. 68]
slender, long-legged flies about 3.5 to 4 mm long. Bristles are few. The only
North American species is mostly black with coarse yellow setulae; the antennae,
front of head and legs are yellow. The wings are faintly patterned with pale
brown patches. The head is almost globose, slightly longer than high, with prominent
compound eyes and fine, short setulae on the antenna and its arista, which arises
on the basal half of the ovate third segment. At the level of the anterior ocellus,
the frons is wider than the compound eye; frons width is equal in males and
females. There are three orbital bristles followed by a row of fine short setae
reaching the level of the antenna. No vibrissae occur; one inner and one outer
vertical bristles are present. The thorax is elongate, almost twice as long
as wide. The wing has a strong subcostal break near the end of vein R1; Sc fades
just before this break. The fork of Rs is strongly divergent. Vein A1 does not reach the wing margin. The legs are slender with fore coxa distant
from middle coxa; bristles lacking except for a short apical one on the middle
Little is known of the
biology of these flies. The larvae have been collected from under the bark of
World wide, the family Strongylophthalmyiidae
contains 33 known species in two genera: Nartshukia with one species
in Vietnam and Strongylophthalmyia with 23 species in the Oriental and
Australasian regions, eight in the Palaearctic region and one in the Nearctic.
These flies have long been placed in the Psilidae, but the family is probably
most closely related to the Tanypezidae. The sole described North American species, Strongylophthalmyia angustipennis Melander was discovered and described
from Puget Sound in Washington; it ranges from BC east to Nova Scotia and south
to Massachusetts, Michigan and Wyoming. It is the basis for the description
Family PSILIDAE (Rust Flies) [Fig. 69]
Members of the Psilidae are small to medium-sized flies
(Nearctic species are 3 to 8 mm long), rather slender and with only sparse bristles.
The body colour ranges from yellow and red to brown or black; the wings are
usually clear, yellowish or smoky, sometimes with the crossveins or wingtip
darkened. The head is circular or triangular in profile with the frons projecting
anteriorly and the face below the antennae strongly sloped backwards. The compound
eyes are variable in size, but the back of the head below them is somewhat swollen.
The antenna ranges from short to rather long, the third segment (and sometimes
also the first two) often elongate (Loxocera) and bearing a setulose
arista on the basal half. Head bristles are few and variable, but there is always
at least an inner and outer vertical bristle on each side; vibrissae are absent.
The wing has a strong subcostal break well before the end of R1;
a clear strip in the wing membrane obliterates the end of Sc and reaches or
crosses R1. The outer end of cell cup is squarely truncate
and vein A1 fails to reach the wing margin. The legs lack bristles,
but there are longer setae on the tips of the tibia. The underside of the femur
of Loxocera species bears a pad of short dense setulae near the tip.
Larvae feed in the roots
and stems of many kinds of plants (recorded hosts include sedges, rushes and
lupines); a few species are pests of crops. The most injurious species is Psila rosae (Fabricius), the Carrot Rust Fly, which tunnels in the roots
of carrots, parsnips and celery. Larvae also live under the damaged bark of
trees. Adults rest on foliage, especially in the shade; some species are
attracted to tree sap.
The Family Psilidae is
mainly Holarctic with a few species scattered in the southern hemisphere. It
contains seven genera and about 200 species; three of these genera and 31
species occur in North America. From the literature and collection records of BC
psilids there are at least 13 species in three genera in the province. Psila contains at least six species in BC: P. dimidiata Loew, a
yellow and black species, is boreal; the all-black P. washingtona Melander ranges from Alaska to Washington; the garden pest P. rosae, a
European immigrant, is dark green with yellow head and legs. Loxocera
microps Melander and L. collaris Loew are western. Chyliza
erudita Melander and C. notata Loew range transcontinentally; C.
scrobiculata Melander and C. leguminicola Melander occur from BC to
Oregon. The latter has been reared from Lupinus polyphyllus Lindl.
(Beach Flies or Lauxaniid Flies) [Fig. 70]
Small robust flies, 2.5
to 5.5 mm long. Yellow, brown, black or a combination of these colours, dull
or shiny, sometimes with dark spots or vittae. The shape of the head is quite
variable, but the eyes are bare or sparsely micropubescent, and the antennal
arista is bare to long plumose. The vertex is not strongly excavate, but rounded
or carinate. Vibrissa are absent, and the postocellar bristles are distinctly
convergent. There are four pairs of strong backward leaning bristles between
the eyes. The thorax has the metepisternum bare, and the posterior thoracic
spiracle lacks both bristles and outstanding setae on the lower margin. The
legs usually have a preapical dorsal bristle on all tibiae, but sometimes this
is absent on the hind tibia. The middle tibia have one to three apical spurs,
the hind tarsus is sometimes ornamented, and the fore femur may have a ctenidium.
The wings are often tinged with yellow, and sometimes spotted or clouded. The
costal vein C is without a subcostal break and ends at M1, while
Sc is complete and separate from R1.
Adults are normally found
in woodlands and in dense vegetation by water in the shade. They may come to
light and to traps baited for fruit flies or flesh flies. Larvae are saprophagous,
and typically live in leaf litter, vegetable trash, in rotting tree stumps,
dung and bird’s nests.
The family, often previously
called the Sapromyzidae, occurs on all continents, except Antarctica. Worldwide
there are about 1,600 species, in some 128 genera. There are 28 genera and some
158 species in North America, with 104 species reported from Canada. At least
nine genera occur in British Columbia. Species of Calliopium, which are
shiny black, sometimes with yellowish legs include C. livingstoni (Coquillett), and C. quadrisetosum (Thomson). Camptoprosopella with a flat face
and sometimes a median black spot, includes a species near C. borealis Shewell. Homoneura, with ctenidium on the fore femur, and two apical
spurs on the middle tibia, includes H. inaequalis (Malloch), H. lamellata (Becker), H. occidentalis (Malloch) and H. shewelli Miller. There
are at least four species of Minettia, including the introduced European M. rivosa (Meigen), and at least four species of the genus Sapromyza Fallén.
with the arista thickly white pubescent is represented by the Holarctic L.
cylindricornis (L.) and the Narctic L. nigrimana Coquillett. So far,
only one species of Lyciella Collin has been detected, the yellow to
brownish European L. rovida (Fallén). The genus Poecilolycia Shewell is present in that there are two species, namely P. annulata (Melander) and P. spatulata Shewell in our collections, together with
an undetermined species of Poecilominettia Hendel.
(Aphid Flies) [Fig. 71]
Small and rather robust
flies, 1.0 to 4.0 mm long. Most species are silvery gray to brown, and usually
densely pruinose, but they can also be shiny black, often with brown stripes
on the thorax, and black spots or bands on the abdomen. The head is as broad
as or broader than the thorax, the compound eyes being bare or with short pubescence.
The ocellar triangle is occasionally enlarged and prominent. Vibrissa are absent,
and there are from zero to three pairs of fronto-orbital bristles. The antennae
are short and porrect. The thoracic scutum bears neatly arranged setulae and
bristles, and the scutellum has just four long setae. The legs are rather weakly
bristled, except for the fore femur which have strong bristles. All tibiae lack
a preapical dorsal bristle. The wings are usually uniformly milky hyaline, but
occasionally have brown markings. The costal vein C is unbroken, and Sc is complete
and free. The radial vein R is bent forward close to Sc, and ends close to the
apex of Sc. The A1 vein is abruptly terminated in the basal third
to half of the wing.
Very little is known about
the biology of most adults. The larvae of most species are free-living predators
of adelgids, aphids, coccids and scale insects.
About twenty genera are
known worldwide. There are from 100 to 150 species in North America, but over
half are still undescribed, since only 55 are described to date in nine genera.
It is estimated that some 105 species occur in Canada. The family is poorly
studied in British Columbia, but there are at least four genera, Chamaemyia Meigen, with three European species C. geniculata (Zetterstedt), C.
herbarum (Robineau-Devoidy) and C. juncorum (Fallén), Leucopis Meigen (L. ocellaris Malloch, L. pulvinariae Malloch), Plunomia Curran (P. elegans Curran, P. transversa Malloch) and Pseudodinia Coquillett (P. nitens (Melander & Spule), P. varipes Coquillett).
Family COELOPIDAE (Seaweed Flies) [Fig. 72]
strongly bristled flies, 3.7 to 8.9 mm long. Black or grayish-black in colour,
shiny or subshiny. The head has the face strongly concave in profile, and the
compound eyes are oblique. The antennae are short, and appressed to the face.
The thorax is distinctly flattened, with the metepisternum setose below the
posterior thoracic spiracle. This latter spiracle lacks bristles on the lower
margin. The fore femora are strongly swollen, and tibiae on all legs have a long
dorsal preapical bristle. The wings lie flat on the abdomen, with the wing blade
posterior to cell dm frequently folded under and closely appressed to the
ventral surface, of the anterior portion of the wing. The veins are generally
bare, but the upper and lower surfaces of the stem of R, and the upper surface
of the apical third of R1 are sometimes setose. The costa is without
a subcostal break and without obvious spines. The subcosta is complete, and
A1+CuA2 extends to the wing margin.
Seaweed flies, as the
common name suggests, are found on sea coasts, associated with seaweeds. The
larvae live in rotting seaweed, and breed in vast numbers, the adults often
occurring in dense swarms around kelp.
Worldwide there are about
30 described species in nine genera. Two genera and five species occur in North
America, with four of these species recorded from Canada. The abundance and
strength of bristles of the body and legs, especially in males, varies greatly
within some species. As a result, this variation has produced a great deal of
confusion in taxonomy at the species level. Western North American species in
the old literature were called Coelopa frigida (Fabricius), but his Holarctic
species evidently is confined to the Atlantic and Arctic coasts. Species in
British Columbia have been identified as C. nebularum Aldrich and C.
stejnegeri Aldrich. Both of these species have a range extending to Alaska
and St. Paul Island in the Bearing Sea. C. vanduzeii Cresson which
ranges from California to southern Alaska has also been identified from BC.
Family SEPSIDAE (Black Scavenger Flies) [Fig. 73]
Slender flies, 2 to 6 mm
long, mostly shiny black, but also can be dull black, brownish or yellowish. The
head is more or less globular, with large compound eyes and bare antennal
arista. The thorax has a silvery pruinescence on at least part of the pleuron,
and the posterior thoracic spiracle has one or more fine bristles on the lower
margin. The legs are slender, and males have the fore femora, and often also the
fore tibiae with characteristic bristles, tubercles or emarginations, for
grasping the base of the wing of the female during copulation. The middle tarsus
of the male sometimes has enlarged or varicolored segments, and the hind tibia
often has a slit or elongate area (osmeterium). The wings are narrow and
hyaline, and usually with a dark spot near the tip of vein R2+3. The
wings are also sometimes blackish at the base. The costa is without a subcostal
break. The abdomen is usually elongate, and often constricted near the base,
giving these flies an ant-like appearance.
Adults are scavengers, and
most often can be caught by sweeping grass in meadows or woods, or around or on
dung. When walking about these flies repeatedly and characteristically flip
their wings outward. Larvae are often found in carrion or excrement. The
Sepsidae with about 250 described species in 21 genera occur worldwide with
numerous species often present on more than one continent. There are 34
described species reported from North America in 11 genera, but there are
numerous others that are either undescribed or undetermined described species.
The family is not well studied in British Columbia, so the number of species is
uncertain although at least 7 described species in 5 genera are known from the
literature and collections of BC Diptera. These species include: Decachaetohora aeneipes (Meijere), an immigrant in the northwest from
Asia; Meroplius sterocoraria (Robineau-Desvoidy); Sepsis
biflexuosa Strobl; Sepsis puncta (Fabricius);and Themira
putris (Linnaeus). The latter four species are Holarctic in their
Family DRYOMYZIDAE (Dryomyzid Flies) [Fig. 74]
Moderately bristly to
quite setose flies, 4 to 12 mm long, yellowish, brown or dark grey in colour.
Head with face convex in middle, and with clypeus large and prominent in
profile, bulging below lower margin of face. The vertex is not strongly
excavated, and the postocellar bristles vary from slight convergent to greatly
divergent. Vibrissae are absent, and the antenna have a short pedicel. The
thorax is somewhat longer than wide, and the metepisternum is bare. The
scutellum has two or three pairs of bristles, and the posterior thoracic
spiracle is lacking both bristles and outstanding setae. The tibiae with dorsal
preapical bristles, and males may have an apicoventral projection on the first
segment of the fore and hind tarsi. The wings are hyaline to smoky or tawny, and
sometimes dark brown spots are present on crossvein r-m and on the posterior
crossvein. The costa lacks a subcostal break, and the subcosta is complete to
the costa at some distance proximal to the tip of vein R1. The costa
may have costal spines, and crossvein bm-cu is always present.
Species of Dryomyza have been reared from decaying organic matter, including decaying fungi,
carrion, and dung. Members of the subfamily Helcomyzinae (often now considered a
separate family) have been reared from seaweed.
The subfamily Dryomyzinae
is restricted to the Holarctic region, with currently 20 described species in
the two genera. The Helcomyzinae are restricted to marine coasts and occur worldwide,
with 13 species in six genera described to date. There are nine species of Dryomyzinae
in North America, with two described genera. There are also two genera of Helcomyzinae
in North America, each with a single species. Nine species of Dryomyzidae are
reported to occur in Canada, at least six of which are known to occur in British
Columbia. The Holarctic Dryomyza anilis Fallén occurs along the Pacific
Coast north to Alaska and is a robust, yellowish species with yellowish hyaline
wings and clouded crossveins. Three other species of Dryomyza, namely D. flaveola (Fabricius), D. melanderi Steyskal and D. setosa (Bigot) have also been reported from this province. One species of Oedoparena, O. glauca (Coquillett) occurs from Alaska to California, and can be separated
from species of Dryomyza by having three pairs of scutellar bristles,
whereas only two pairs occur in Dryomyza. O. glauca is a lead-coloured
fly with grayish hyaline wings, yellowish costal cell, and yellow halteres.
The only species of Helcomyzinae known from British Columbia is the large, gray,
11 mm long Helcomyza mirabilis Melander. As noted above, these flies
are to be found on sea beaches associated with wrack beds, the species also
being known from Oregon and Washington.
Family SCIOMYZIDAE (Marsh Flies) [Fig. 75]
Slender to robust flies,
1.8 to 11.5 mm long. Colour varying from shiny black to dull gray, brown,
reddish or yellowish. Head with face usually concave in profile, the frons being
wide in both sexes, and the vertex not strongly excavate. The postocellar
bristles are strong and parallel or slightly divergent. The compound eyes are
prominent and bare, and vibrissae are absent. The antennae are
characteristically porrect, with the pedicel usually elongate. However, the
antennae can be short or long, but typically the arista is short, pubescent to
plumose. The thorax lacks a precoxal bridge and the metepisternum is bare. The
posterior thoracic spiracle also is without either bristles or setae. The legs
typically have the femora well developed and usually strongly bristled. One or
more of the tibiae also have a preapical dorsal bristle. The wings are usually
longer than the body, and are immaculate or heavily patterned or spotted. The
costa lacks spines and is without a subcostal break. The subcosta is complete,
being free from vein R1 distally, and ending in the costa.
Adults can often be swept
from vegetation along streams or ponds. Larvae are associated with freshwater or
terrestrial molluscs, and are parasitic or predaceous. A few may be
Worldwide there are some
600 described genera in 60 genera. The North American fauna has some 194 species
in 21 genera. So far, 110 species are reported to occur in Canada. There are
many specimens from British Columbia still to be determined, but there are at
least 39 species in nine genera known from the literature and from collections
of BC Diptera. Dictya Meigen and Pherbellia Robineau-Desvoidy
with 4 species each, Sepedon Latreille with 8 species, Tetanocera Duméril with 16 species are the most speciose genera in BC.
Species of Dictya which have a white face with a central black spot include D. expansa Steyskal, D. montana Steyskal and D. stricta Steyskal. Pherbellia species which have the fore tibia with a single preapical dorsal bristle and
a non-shiny frons include P. albocostata (Fallén), P. quadrata Steyskal, P. tenuipes (Loew) and P. vitalis (Cresson). Sepedon species which lack ocellar bristles, have one orbital bristle on each side,
and have the postocellar bristles well developed include S. armipes Loew, S. borealis Steyskal, S. fuscipennis Loew, S. lignator Steyskal, S. praemiosa Giglio-Tos, S. pseudoarmipes Fisher &
Orth, and S. pusilla Loew. Tetanocera species with their black
arista include T. annae Steyskal and at least 15 other species. Trypetoptera
canadensis (Macquart) which occurs in BC, also has a black arista, but has
the subalar sclerite with vallar bristles, unlike Tetanocera species.
Family HELEOMYZIDAE (Heleomyzid Flies) [Fig. 76]
Robust and bristly flies,
3.0 to 7.0 mm long, yellow, reddish yellow or reddish brown to black in colour,
and often distinctly pruinose. Head with one to three pairs of orbital bristles,
and with ocellar bristles, arising on ocellar triangle above anterior ocellus.
One or two pairs of oral vibrissae are present, and the postocellar bristles
are strong and convergent. The antennae are short, and the arista minutely pubescent
to plumose. The thoracic scutellum has two or three pairs of strong bristles.
The legs are moderately bristled; middle and hind tibiae usually have a preapical
dorsal bristle although this may be fine in some genera such as Borboropsis Czerny. The wings are usually hyaline, but sometimes faintly yellowish or brownish.
The wing surface may be mottled with contrasting whitish and dark gray areas,
the crossveins are often clouded and the longitudinal veins fuscous. The costa
extends to the end of vein M1+2 and has a distinct subcostal break,
but no humeral break. The costa also usually has strong and conspicuous spines.
The subcosta is usually completely separate from vein R1, ending
in the costa sometimes close to vein R1, and a pterostigma is often
present. Vein CuA2 is short, and fuses with vein A1, the
combined vein often nearly reaching the wing margin.
Adults are commonly
collected in moist, shaded area. Many larvae breed in fungi, but those of the
subfamily Heliomyzinae breed in decaying plant and animal matter, and are known
to occur in bird’s nests, mammal burrows, bat caves, carcasses of large mammals,
Often workers now consider
the Heleomyzidae to include the family Trixoscelididae as the subfamily
Trixoscelidinae. We have maintained them as separate families to allow for easy
generic identifications using the Manual of Nearctic Diptera. Worldwide there
are about 65 described genera and over 500 described species in the
Heleomyzidae, in the broad sense. There are 27 described genera with 120 species
of heleomyzids (in the strict sense) in the Nearctic. There are 19 described
genera with 53 species known to occur in BC based on the published literature
and collections of BC Diptera. At least four species Amoebaleria
scutellata Garrett, Anypotacta aldrichi (Garrett), Heleomyza
genalis (Coquillett) and Neoleria diversa (Garrett) seem to be
At least another nine species
also occur in Europe as well, but some may be truly Holarctic and not alien
introductions. This latter group includes Aecotheca fenestralis (Fallén), Amoebaleria flavotestacea (Zetterstedt), Borboropris fulviceps (Strobl), Heleomyza brachypterna (Loew), H. pleuralis (Becker), H. serrata (Linnaeus), Neoleria inscripta (Meigen), Suillia
nemorum (Meigen) and Tephrochlamys rufiventris (Meigen).
Family TRIXOSCELIDIDAE (Trixoscelidid Flies) [Fig. 77]
Small flies, 1.5 to 3.0 mm
long. Legs, face, antennae and a portion of the frons yellow, but in species of Zagonia Coquillett, the whole body is yellow. The body is mostly
pruinose, but the abdomen is sometimes glabrous. The face is slightly concave,
and the ocellar bristles arise just outside the ocellar triangle, being beside
or slightly below the anterior ocellus. Vibrissae are present, and the
postocellar bristles are strong and not divergent. The vertex is not strongly
excavated, and the antenna may be partly hidden in an antennal socket. The
thoracic scutellum has four bristles. The fore femora are slightly swollen, and
all tibias have a preapical dorsal bristle. The middle tibias also have one or
more apicoventral bristles. The wings are hyaline, and sometimes fuscous along
the veins and crossveins, but the wing can be blackened with conspicuous hyaline
spots. The costa has a subcostal break, but lacks a humeral break, and extends
to the end of vein M1+2. The subcosta is complete and free from vein
R1, ending in the costa near vein R1, near the basal third
of the wing.
Adults are frequently
collected on flowers or vegetation. However, nothing is known about the larval
biology and habitats.
This family is often now
included within the Heleomyzidae. If kept separate, the Heleomyzidae are
recognized by the ocellar bristles arising on the ocellar triangle, above the
anterior ocellus, whereas in the Trixoscelididae, these bristles lie just
outside the ocellar triangle.
Three genera and 27
species are reported in North America, with six species occurring in Canada.
There are 4 described species in two genera known to occur in BC, based on the
published literature and collections of BC Diptera. The two most common species
in BC appear to be the European Trixoscelis frontalis (Fallén) with the
body predominantly gray, and the Nearctic Zagonia flavicorvis Melander,
with the body entirely or predominantly yellow.
Family SPHAEROCERIDAE (Lesser or Small Dung Flies) [Fig. 78]
Lesser dung flies are
small, to minute, robust, 0.9 to 5.0 mm long, easily recognized by the short,
thick basal segment to the hind tarsus. These are generally dull coloured flies,
often black or dark brown, but sometimes brown or with head or legs yellowish;
some tropical groups of lesser dung flies are highly coloured. The frons is
broad, and slightly narrowed anteriorly, typically with two proclinate or
lateroclinate bristles. Vibrissae are present, and the antennae are short with
the arista preapical or subapical. The thoracic scutum is usually setose, but is
warty in some species of the subfamily Sphaerocerinae. The anepimeron is bare.
Legs with the femora, especially the hind femora somewhat swollen, and with the
hind tarsus distinctive with its swollen basal segment. Wings may be fully
developed (macropterous), or reduced (brachypterous), or may be totally absent
(apterous). If macropterous, the wings are rarely spotted, with costa ending at
vein R1+2, or at vein R4+5, or between them, and with
costagial, humeral, and subcostal breaks. The subcosta is incomplete, and vein
A1 never reaches the wing margin.
North American lesser dung
flies have larvae that are scavengers, commonly associated with decaying organic
matter, including animal dung, carrion, cave debris, compost, conifer litter,
dead vegetation, fungi, leaf litter, mammal nests and supralittoral seaweed
There are over 1340
described species of lesser dung flies in 111genera worldwide with 38 genera and 273 species reported from the Nearctic. At least 25 genera and 91
species are known from British Columbia. Two endemic species are Phthitia
squamosa Marshall and Minilimosina sitka Marshall which are known
from the Sitka spruce forests of the Carmanah Valley on Vancouver Island. Coproica ferruginata (Stenhammer), Copromyza equina Fallén and Norrbomia sordida (Zetterstedt) are largely cosmopolitan species which
are commonly found in BC.
Family CHYROMYIDAE (Chromyid Flies) [Fig. 79]
Very small, Drosophila-like flies, 1.0 to 4.5 mm long, usually yellow in colour. Head
with frons narrowed anteriorly, and with ocellar bristles usually relatively
strong. The postocellar bristles are usually present, and convergent. Vibrissae
are present, but rather weak, and the antennae are short, with the arista
microscopically pubescent. The thorax has yellow bristles and spines, and the
proepimeral bristle is absent. Also, the proepisternal bristle is usually
absent, while the anepimeron is bare. The legs are weakly bristled, with the
fore and hind femora in the male frequently enlarged. All tibiae lack a dorsal
preapical dorsal bristle. The costa has a subcostal break only, and extends to
vein M1. Subcosta is complete, but weak on the apical one-fifth, and
joining the costa very close to the insertion of vein R1. Cell
cup is present at the base of the wing posteriorly.
Adults have been swept
from foliage of shrubs and herbs, especially at margins of creeks and ponds.
Adults of the genera Chyromya Robineau-Desvoidy and Gymnochiromyia Hendel have been reared from bird’s nests, mammal burrows, and wood debris of
hollow trees. However, adults of species of Aphaniosoma Becker appear to
frequent grasses and sedges on seashores, and around alkaline or saline ponds or
Worldwide, three genera
and about 40 species are reported, with all three genera and nine species
occurring in North America. Seven described species in three genera have been
collected in Canada, but so far only one species, the Nearctic Gymnochiromyia
concolor (Malloch) is known to occur British Columbia based on the published
literature. There are at least 3 species occurring in BC, including one that is
undescribed, based on collections of BC Diptera.
Family DROSOPHILIDAE (Pomace Flies, Vinegar Flies, Lesser Fruit
Flies) [Fig. 80]
Nearctic Pomace Flies are
small to medium-sized, 1 to 6 mm long; body colour varies from yellow to brown
or black, and can be shiny or grey pruinose. There are frequently stripes or
spots on the thorax and abdomen. The compound eyes usually are covered in a
distinct micro-pubescence and are often bright red in life. The head has three
orbital bristles; usually the back two curved rearward, the front one forward.
The ocellar bristles vary from large to small, as do the postorbitals; the
latter are convergent and are almost always present. There is one to several
strong vibrissae. The antennal arista is normally plumose, although it can be
bare or have reduced branching. The scutum usually has two postsutural
dorsocentral bristles. The tibiae have apical and preapical dorsal bristles. The
wing has both humeral and subcostal breaks of the costa; the end of the subcosta
is usually vestigial. Crossveins r-m and dm-cu are always present; cells bm and
dm either separated or joined.
The larvae of pomace flies
mostly eat yeasts and other microorganisms in fermenting organic matter. Adults
live around garbage, compost, rotting fruits and vegetables, decomposing cacti,
sap from tree wounds, fungi and dung. A few species can be annoying pests in
markets, breweries, bakeries and canneries. Some are used as laboratory animals
for genetic and physiological research because they are small, fecund and so
easy to rear and maintain. Many species of Scaptomyza Hardy are leaf
miners; larvae of Cladochaeta Coquillett are ectoparasites of cercopid
nymphs; species of Pseudiastata Coquillett prey on mealybugs.
The family Drosophilidae
is speciose, with about 60 genera and 3000 species worldwide many of them in
the tropics. North America has about 182 described species in 16 genera Eight
genera and about 35 described species are known to occur in BC based on published
records and collections of BC Diptera. The family is dominated by the genus Drosophila Fallén, which has about 1600 described species worldwide,
about 114 in the Nearctic and over 20 in BC. Drosophila melanogaster Meigen is probably the most familiar species in the genus; it is certainly the
best known scientifically because of its wide use in research laboratories.
It is common in BC as are D. buskii Coquillett and D. funebris (Fabricius), European species now widely cosmopolitan; both are particularly
attracted to sour milk and rotting potatoes. D. hydei Sturtevant
is also cosmopolitan and widespread across southern BC, as is D. pseudoobscura Frolova (a native New World species) which is common in the southern Interior. D. athabasca Sturtevant and Dobzhansky, is more common in eastern
BC, especially in and around the Rocky Mountains.
Cacoxenus guttatus Hardy and Wheeler is a native of northwestern North America; the larvae feed on
stem rusts on Lodgepole Pine (Pinus contorta Douglas). Chymomyza
aldrichii Sturtevant lives in the boreal forests from Alaska to Maine, where
it develops in logs of White Spruce (Picea glauca (Moench) Voss) and
Trembling Aspen (Populus tremuloides Michaux). C. caudatula Oldenberg is a Holarctic relative, also common in the western mountains. Cladochaeta inversa (Walker) ranges transcontinentally; it is
ectoparasitic on spittlebug nymphs of the genus Clastoptera Germar – an
unusual habit for a drosophilid. Species of Scaptomyza are mostly leaf
miners; there are at least seven reported from BC, including S. adusta (Loew) a species widespread in North America and in the
Neotropics, and S. graminum (Fallén) a Holarctic species. S. montana Wheeler is boreal; the larvae mine in the leaves of
Common Water Cress (Nasturtium officinale R. Br.). The introduced S. pallida (Zetterstedt) is now cosmopolitan; it lives in decaying
vegetable matter. Leucophenga montana Wheeler ranges from BC to Utah and
California; it breeds in fungi. Stegana coleoptrata (Scopoli), a
boreal, Holarctic fly that develops under the bark of trees such as pine, larch
and birch, and is the only species of the genus reported from the
Family DIASTATIDAE (Diastatid Flies) [Fig. 81]
Diastatids are small flies,
about 2.5 to 4.0 mm long, grey-brown, with patterned wings. The head is higher
than long and the frons narrows from the vertex to the antennae. The vertical
bristles are strong; the inner pair is often longer than the outer pair. The
postocellar bristles converge and the ocellar bristles arise prominently behind
the front ocellus. Two orbital bristles of unequal size curve backward and a
third one points forward. The face is flat; the vibrissa is strong, lying in
front of a row of 5 to 7 subvibrissal setae. The compound eye is bare. The antenna
has the second segment swollen above; the third segment points downward and
bears an arista that ranges from almost bare to feathery. The scutum has short,
depressed setae; two postsutural dorsocentral bristles are present. The scutellum
is flat, lacks setulae, but bears two pairs of bristles. The wing is usually
twice as long as wide; the anal lobe and alula are weak to absent. The costa
is weakly, but distinctly spiny and has both humeral and subcostal breaks. It
extends to the end of vein M1+2 at the wing tip, but is weak past
the end of vein R4+5. The subcosta is incomplete. Crossvein r-m is
basal to the middle of cell dm and the cossvein dm-cu is about as long as the
part of vein CuA1 apical to dm-cu. Vein A1 is weak and
short. The wing is usually spotted with brown or has white spots on a brown
background. The legs are slender; the front femur always has a comb of short
stout setae on the lower front margin of the apical half. All tibiae have a
dorsal bristle just before the tip.
Adults are encountered
around rich herbaceous vegetation in moist woodland and on the edges of
peatlands and other wetlands. The males of some species wave their spotted and
reflective wings during courtship displays. The biology of the immatues stages
The Diastatidae is a nonspeciose
family, mostly Holarctic in distribution, containing about 40 described species
in four genera worldwide; one genus is extinct and known only from Baltic amber.
North America has six described species in Diastata Meigen and Campichoeta Macquart; three in the former genus and one in the latter are recorded in BC. Diastata eluta Loew ranges from Alaska to Idaho and Oregon; D. modesta Melander is recorded from BC and Washington. The third species
in the province, D. vagans Loew, is boreal. Campichoeta griseola (Zetterstedt) lives in Eurasia as well as in the boreal and
western montane forests of North America.
Family EPHYDRIDAE (Shore Flies) [Fig. 82]
Ephydrids are small to
medium-sized flies (1 to 11 mm long), usually dark and dull in colour, but
highly variable in structure and difficult to characterize. The head has the
frons usually wider than long; the face is variable in form, setulose and
arched, often bulging, tubercles and ridges are often present. The subcranial
cavity is often large and gaping and the mouthparts, if large, can be pendulous.
Fronto-orbital bristles often prominent, curving forward or backward, often in
many species, strongly projecting laterally. The antennae are short, the second
segment often has a single bristle above; the third segment bears a dorsal
arista, which is bare, finely setulose or comb-like, with any aristal rays
almost always on the upper surface only. The thorax is extremely variable in
surface features – shiny, dull, or densely pruinose, sculptured or smooth. The
wing is clear or spotted and has with both humeral and subcostal breaks of the
costa; the subcosta is incomplete and vein R1 joins the costa before
the middle of the wing. Cells bm and dm are not separated by a crossvein; cell
cup is absent. The fore and middle femora often have spines or bristles
below; the forelegs of Octhera Latreille are raptorial. A preapical
dorsal bristle occurs only on the middle tibia. The empodia and pulvilli are
frequently reduced or absent in Subfamily Ephydrinae.
Shore flies typically live
in aquatic and semiaquatic habitats. Many species develop along the muddy shores
of marshes, ponds and streams, but many also live in marine marshes, tidal pools,
and the alkaline lakes of arid and semiarid environments. It is in these harsh
saline habitats that the most distinctive forms have evolved and where the family
has reached its greatest biological importance. In these habitats the both immature
stages and adults can be so abundant that they are significant food for wildlife,
especially waterfowl and shorebirds. The family is pre-eminent in its ability
to withstand the osmotic pressure of salt water. Most larvae feed by filtering
microorganisms such as bacteria, algae and yeasts from the water and mud, but
others feed on excrement in places such as cess pits and in the sludge found
in sewage filters; from sewage it is a short step to feeding on decomposing
carrion and carcasses. In salty aquatic habitats, especially, there is a strong
trend to carnivory; Octhera larvae eat chironomid midge larvae. Others
exploit the many invertebrates that fall into the water and cannot escape. The
carnivorous larvae of Helaeomyia petrolei (Coquillett) live in pools
of crude petroleum that flow from the ground in California; they feed on organisms
trapped in the oil.
Some larvae of genera such
as Hydrellia Robineau-Desvoidy and Psilopa Fallén are leaf or stem
miners; some species of the former genus develop in plants far from water. Other
species of Hydrellia, when abundant, can damage crops of watercress, rice
and other irrigated cereals. Species of Hydrellia mining the leaves of
the aquatic genus Potamogeton Linneaus can access oxygen by inserting
their posterior spiracles (which open near the ends of sharp, hollow spines)
into the leaf tissue.
Most adult shore flies
feed on unicellular algae and other microroganisms. Both the adults and larvae
of several shore fly species feed on the bacteria and cyanobacteria growing in
algal mats in hot springs. Adults of Ochthera feed on small insects and
still others eat nectar and leaf tissue.
The family Ephydridae is
speciose, with about 1800 described species in 114 genera worldwide. The 460
known North American species are sorted into about 70 genera, the largest of
which are Hydrellia (70 species) and Notiphila Fallén (55
species). BC has about 37 recorded genera and 95 species. Hydrellia, with
about 13 species known in BC, is the province’s most speciose ephydrid genus.
Small, usually about 1 or 2 mm long and with densely micro-pubescent compound
eyes, Hydrellia species are found mostly in grassy, sedgy areas. The
larvae mostly mine in the leaves of grasses and aquatic plants such as Eleocharis Brown (eg, H. tibialis Cresson) and Potamogeton (eg, H. pulla Cresson). H. griseola (Fallén) is Holarctic and widely distributed across North
America. In BC it ranges from Atlin to the Kootenays; elsewhere, it can be a
pest of rice and wild rice (Zizania Linneaus). Atissa pygmaea (Haliday) is also a tiny Holarctic species; it ranges all the way
to South America. Only 1 mm long, it is almost completely white
The ten BC species of Parydra Stenhammar live mainly around the fresh waters of lakes, ponds and streams. Parydra aurata Jones is a Cordilleran species ranging south to NewMexico; P. borealis (Cresson) and P. varia Loew are boreal.
Species of Scatophila Becker are also common around small streams; three
species are recorded from BC -- S. despecta (Haliday) is perhaps
the most widespread of the genus in North America. At least three species of Ephydra Fallén live in BC around marshes and alkaline lakes; perhaps
the most common is E. riparia Fallén, widespread in Europe and
all across North America.
Many BC species inhabit
saline environments. Particularly remarkable in the dry Interior of the province
is Hydropyrus hians (Say), which ranges over the west wherever alkaline
ponds and lakes occur. In the Cariboo the larvae and pupae are found massing in
huge numbers in almost completely saturated sodium carbonate solutions, the
adults swarming on the salt crusts and on the water surface itself. Clanoneurum americanum Cresson is also common in salty habitats in both
western North America and along the Atlantic coast and Coenia curvicauda (Meigen) is frequent in coastal and inland salt marshes transcontinentally. Glenanthe litorea Cresson lives in coastal salt marshes from Alaska to
Central America and from the Canadian Maritimes to Texas. Lamproscatella
quadrisetosa (Becker) is a seabeach species on both sides of the
Octhera mantis (De
Geer) is widespread in the temperate northern hemisphere and perhaps is the most
distinctive BC ephydrid. It uses its massive raptorial forelegs to crush small
flies and grab mosquito larvae from the water or chironomid larvae from the mud.
Many ephydrids are subtly colourful at close range including some species that
have brown wing spots. Ilythea spilota (Curtis), a common Holartic
species, is one of these. Others have white spots on dark wings; Scatella Robineau-Desvoidy and its relatives are among these species. Scatella
stagnalis (Fallén) is one of five or six BC species in the genus.
(Odiniid Flies) [Fig. 83]
Odiniid flies are small,
rather stout insects, about 3 to 4 mm long. They are gray, marked with brown;
the wings are spotted or mottled with brown. The head is higher than long; the
frons is as broad as long, equally wide in both sexes. The postocellar bristles
are divergent; the inner vertical bristle is usually stronger than the outer
one; the lower of the three orbital bristles points inwards. The oral vibrissa
is strong, with adjacent bristles decreasing in size rearwards. The antenna is
mostly yellow; the second segment has a dorsal bristle and the globular third
segment bears a shortly setulose arista. The scutellum is large and convex with
two pairs of bristles; the scutum is usually strongly bristled, including four
or five dorsocentral bristles. The wing is short and broad, always darkened
around the subcostal break in North American species. The costa is broken at the
subcosta only, and extends around the wing to R4+5 or M1.
The subcosta is incomplete; R1 lacks setae and joins wing margin near
the subcostal break. Cells bm and dm are complete; the apex of cell cup is convex. Vein A1 does not reach the wing margin. The stout legs
are often yellow and usually the tibiae are banded with brown; the hind femur is
enlarged in males. The legs are moderately bristled; preapical dorsal bristles
are present and are strongest on middle tibia. The abdomen is short and broad;
it is normally grey spotted with brown.
Adult odiniids gather at
wounds in trees, on polypore fungi and rotting tree trunks and stumps. The
larvae are apparently frequently associated with wood boring beetles and moths.
They may feed on fluids of decay or on fungi in insect galleries or decaying
wood; some may parasitize other insect larvae.
Closely related to the Agromyzidae,
the family Odiniidae occurs worldwide. It is divided into ten living genera
containing about 60 described species. In North America, three genera contain
12 species; eight, including the two recorded in BC, are in the cosmoplitan
genus Odinia. Odinia betulae Sabrosky is widespread throughout
North America, including BC. O. xanthocera Collin is Holarctic, but in
North America has been recorded only in BC. O. boletina (Zetterstedt)
is Holarctic and has been recorded from southwestern Alberta; it may occur in
Family AGROMYZIDAE (Leafminer Flies) [Fig. 84]
The Agromyzidae is a large family of minute to small, stocky
flies (1 to 6 mm long) ranging from yellow to brown, grey and black in colour;
often they are black with yellow markings. The wings are normally clear, but
are patterned in some tropical forms. The compound eye is vertical or slanting,
bare or sometimes setulose. There are one to three orbital bristles and one
to five frontal bristles, the lower ones usually angled inwards; the postocellar
bristles diverge. A well-developed vibrissa is present; sometimes several vibrissae
are fused (eg, in males of some Ophiomyza). The third segment of the
antenna varies from small and globular to elongate; the arista is bare or short-setose.
The thorax bears two to five dorsocentral bristles; there are one or two pairs
of scutellar bristles. The wing has the costa ending near vein R4+5 or vein M1 and broken only at the end of the subcosta. Subcosta is
either distinct and joins R1 or is reduced to a fold that may or
may not end in the costa. Cell cup is present; vein A1 fails
to reach the wing margin. The legs lack preapical dorsal bristles on all tibiae.
The abdomen is usually more or less depressed and tapering; six segments are
visible in front of the genitalia.
Agromyzid larvae eat
living plant tissue. Most species feed between the upper and lower surfaces of
leaves, making conspicuous mines, but others attack stems, roots and seeds.
Most, being small and inconspicuous, are more easily recognized by the mines
that they make than they are by the adult insects themselves. Mines can be
blotch-like, linear or serpentine and their location in the leaf can be
diagnostic. Even the distribution pattern of frass can be characteristic. Most
agromyzids limit their development to particular plant species or groups of
related species. Some are more polyphagous, including species such as Liriomyza trifolii (Burgess), which attacks many legumes and other plants
such as tomatoes, cucumbers, asters and chrysanthemums. Many species are pests
of agricultural crops and ornamental plants.
The Family Agromyzidae
ranges throughout the world, inhabiting all environments from arctic tundra to
tropical forests. There are over 2700 species named in 29 genera, but certainly
many hundreds of species remain undescribed. In North America, over 700 species
are described in 22 genera, including almost 200 in Phytomyza and over
100 in Liriomyza. About 75 species in 17 genera are known in BC and over
30 more species are recorded close to the province’s borders, especially in the
Alberta Rockies. About 20% of the species belong to Phytomyza. P.
ilicis Curtis (Holly Leaf Miner) was introduced into western North America
from Europe with its host; by the 1930s was causing considerable damage in south
coast holly farms. Agromyza albitarsis Meigen, one of at least 13 species
in the genus in BC, is Holarctic; its mines in cottonwood and aspen leaves are
familiar. Agromyza pseudoreptans Nowakowski, a Holarctic species, is
widespread in BC; it mines nettle (Urtica dioica Linnaeus) leaves. About
ten known species of Cerodontha develop in grasses, rushes and other
monocots in the province; C. dorsalis (Loew) is one of the more common
Chromatomyia nigra (Meigen) and C. syngenesiae Hardy occur in both the Old and New
worlds; the latter feeds on the weed Senecio jacobaea (Linneaus)(Tansy
Ragwort) and may have been introduced to North America with its host. C.
involucratae Spencer develops in honeysuckles (Lonicera spp.). Eight,
and probably more, species of Liriomyza, includingL. bellissima (Spencer) and L. baptisiae (Frost) are BC natives. The former is common
from Atlin to Osoyoos. The latter lives in southern BC and feeds on lupines. Ophiomyia, including species such as O. coniceps (Malloch), O.
nasuta (Melander) and O. pulicaria (Meigen) mine the leaves of weedy
composites such as dandelion (Taraxacum) and sow-thistle
(Sonchus). Phytobia amelanchieris (Greene) bores in the cambium of
Saskatoon (Amelanchier) bushes
Spencer, K.A. 1969. The
Agromyzidae of Canada and Alaska. Memoirs of the Entomological Society of Canada
Family CLUSIIDAE (Clusiid Flies)
Flies of the family Clusiidae are slender, small to medium-sized
(1.8 to 7.5 mm long), yellow to black species. The bodies are often marked,
but are seldom pruinose. The wings are frequently smoky or marked with brown,
especially at the tips. The head is normally higher than long and wider than
high, flat or concave at the back. The antennae are short -- the first segment
is tiny, the second has a dorsal bristle and often with a characteristic triangular
projection on the outer margin. The third segment is more or less globular,
bearing an arista near the tip; the arista is usually setulose. The ocellar
bristles are short; the postocellars, when present, are divergent. The vertical
bristles are prominent; the inner ones are longer than the outer ones. There
are two to five fronto-orbital bristles. Oral vibrissae are strong and pointed
forward and upward. The wing is usually twice as long as wide with a broadly
rounded tip. Costa normally has a subcostal break and usually rounds the apex
and reaches M1. Subcosta is complete, running parallel to R1.
Cell bm is complete, but vein A1 does not reach the wing margin.
On the legs, most species have well-developed preapical dorsal bristles on at
least the middle tibia. The abdomen is slender and tapered.
Clusiid larvae develop in
rotten wood, mostly under the bark of dead and dying deciduous trees. They can
jump like the larvae of Piophilidae. The adults feed on nectar, sap and decayed
vegetable matter. In some species, lekking occurs, where males aggregate to
interact and attract females. In these situations, male dominance hierarchies
can develop. Males of many species use their patterned wings in mating displays
and head-pushing in male-male interactions sometimes occurs.
The cosmopolitan family
Clusiidae is based on about 220 species in 25 genera; four genera and about 40
species are recorded in North America. However, recent work suggests there are
over 600 species worldwide and almost 400 in the New World. Eight species in
three genera are known to occur in BC from the literature and collections of BC
Diptera. The more common species include, Clusia occidentalis Malloch,
one of three species in the genus in North America, ranges from BC south to
California. It has a yellow face and black spots on the sides of the abdomen and
has been reared from alder trees. Clusiodes albimanus (Meigen) and C.
melanostoma (Loew) are transcontinental species; the former also occurs in
the Old World. The former develops in birch, the latter in poplars.
Family ACARTOPHTHALMIDAE (Acartophthalmidae Flies) [Fig. 86]
Acartophthalmids are dull
grey or black flies only 2.5 to 3.0 mm long; the wings are somewhat infuscate.
The head is higher than long and bears prominent bristles; the compound eyes
are round and finely setulose. The frons is strongly narrowed from the top of
the head to the antennae. There are three fronto-orbital bristles; the upper
is the longest, the lower the shortest.
The ocellar, inner and
outer verticals and postocellar bristles are strong and all about the same
length; the postocellars are widely separated and diverging. The vibrissae are
weak and are accompanied by four or five additional bristles about the same
size. The antennae are short, the third segment is globular with a shortly
setulose arista near the base. The scutum has three or four dorsocentral
bristles; two pairs of bristles on the scutellum. The subcosta is complete,
meeting the costa well before the end of vein R1; the costa is broken
near the humeral crossvein. Cell bm is complete; vein A1 does not
reach the edge of the wing. The legs lack strong bristles; preapical dorsal
tibial bristles are absent.
The habits are poorly known
in this family, and the immature stages are undescribed. Adults sometimes are
seen on logs, stumps and rotting fungi in wet forests. The males often flick
their wings in the manner of otitid flies.
Formerly treated as a subfamily
of the Clusiidae, the Acartophthalmidae consists of only three known species,
two Holarctic and one Palearctic in distribution. Acartopthalmus nigrina (Zetterstedt) ranges from Alaska to the Atlantic Ocean; it has been collected
in southern BC from the Brooks Peninsula on western Vancouver Island to the
southern interior valleys. A. bicolor Oldenberg has not been recorded
in BC although it is known from Canada.
Family OPOMYZIDAE (Opomyzid Flies) [Fig. 87]
Opomyzids are small, slender flies, 2.0 to 4.5 mm long;
the body is yellow, red, brown or black and can be shiny or pruinose. The wings
always have at least a dark spot at the tip; usually there are additional
markings, especially on the crossveins. Some Geomyza species have reduced
wings and are nearly flightless. The head has the frons somewhat narrowed
towards the antennae. There is one strong orbital bristle, the inner and outer
vertical bristles are strong and the postocellar bristles are usually lacking;
if present, they are diverging. No vibrissae occur on the weak vibrissal angle,
but a significant row of setae may be present under the compound eye. The
compound eye is sparsely clothed with short setulae. The third antennal segment
is oval, produced downward; the arista often has the upper setulae longer than
the lower ones. The scutum is strongly bristled; there are three or four
dorsocentral bristles. The scutellum has four bristles, the basal pair are often
weak. The wing is moderately broad to unusually narrow; the alula and anal lobe
are frequently absent. Costa extends to M1 and is broken only at the
end of the subcosta. Subcosta is incomplete; cells dm and bm usually are
incompletely separated; cell cup is present. Vein A1 is
incomplete or absent. There are no dorsal preapical bristles on the
Adult opomyzids usually
frequent moist grassy habitats. The larvae feed within the stems of
The Family Opomyzidae is
small, with about 40 species in four genera; most live in the north temperate
regions, but a few occur in eastern and southern Africa. In North America there
are 13 species recorded in three genera; the largest is Geomyza, with
10 species. All three genera likely occur in BC. Anomalochaeta guttipennis (Zetterstedt) is Holarctic and ranges across the continent in the northern forests;
it has striking dark wings with clear spots. Although not formally recorded
from BC it is known from the adjacent provinces, territories and states and
likely occurs here. Geomyza balachowskyi Mesnil has been introduced
to both coasts from Europe. G. lurida (Loew) ranges from Alaska to California
along the coast; G. monostigma Melander and G. parvistigma Vockeroth
have both been collected in southern BC. Opomyza petri Mesnil is a well-established
introduction to south coastal BC from Europe, where the larvae feed in grasses
such as Holcus lanatus Linnaeus.
North American species
have been monographed by Vockeroth (1961).
Vockeroth, J.R. 1961. The
North American species of the family Opomyzidae (Diptera: Acalypterae). Canadian
Family ANTHOMYZIDAE (Anthomyzid Flies ) [Fig. 88]
Small, slender flies, 2.0
to 3.0 mm long. Shining black to moderately pruinose, yellow to black in colour.
The frons of the head is slightly narrowed anteriorly, and there are one to
three pairs of orbital bristles, with the anterior pair small or even absent.
Ocelli are present, and the ocellar bristles are strong. Post-ocellar bristles
are short, weak and convergent, while there is a row of very weak genal setae
present below the compound eye, ending anteriorly in one or two distinct vibrissa-like
bristles. The compound eyes are bare. The antennae are short, turned downward,
and the arista has short to long setae. The thoracic postnotum has one bristle,
and the scutellum is bare with two short subbasal and two long, apical bristles.
The prosternum and anepisternum are bare. All tibiae lack a dorsal preapical
bristle, and the fore femora usually have a strongly developed ctenidial spine.
Wings are usually slender and unmarked, but rarely can be reduced or even absent.
Wings when fully developed have the costa extending to the apex of vein M, with
a subcostal break, while the subcostal vein is incomplete, and not reaching
the costa. Cell cup is present at the base of the wing, while the halteres
may be well developed or rudimentary. The abdomen is more or less depressed.
Adults are commonly swept
from grass or low vegetation, especially in marshy areas. Larvae are associated
with Juncus, Typha, Elymus, etc., living between the
closely fitting leaf blades of terminal shoots.
Worldwide there are about
53 species in 14 genera. Four genera and 22 described species occur in
North America, with many additional species awaiting description. Stiphrosoma
humerale Rohacek & Barber is a recently described species that occurs in
British Columbia, at Robson. Anthomyza tenuis (Loew) is the other
described species known from BC at Robson and at Likely.
Family PERISCELIDIDAE (Periscelidid
Flies ) [Fig. 89]
Periscelidids are small Drosophila-like flies, 3.0 to 4.0 mm long. Colour dull grayish-black or
brownish-black. Head broader than high, narrowed below the antennae. The frons
has one pair of orbital bristles, and the postocellar bristles are strong and
divergent. Ocelli distinct and single pair of ocellar bristles distinct.
Antennae arista plumose. Compound eyes with short sparse pubescence. Thorax with
propleura and scutellum bare, the latter with four bristles. Legs short and
stout, with tibiae frequently banded. Fore and middle femora each with row of
fairly strong posteroventral setae. Preapical dorsal bristles on tibiae
undeveloped. Wings short and broad with milky, sometimes brownish markings.
Costal vein without subcostal or humeral breaks. Subcosta is incomplete and not
reaching costa, but vein R1 joining costa near middle of wings, and
veins R4+5 and M not convergent. Veins CuA2 and
A1 atrophied. Abdomen rather broad and dorsoventrally
Adults frequent wounds and
sap fluxes on trunks of deciduous trees. Adults of Periscelis wheeleri (Sturtevant) has been reared from larvae found in galleries of the cerambycid Sternochetus lapathi (L.) on willow (Salix sp.) in British
The Periscelididae has
primarily a Neotropical distribution, with about 9 genera and fewer than 60
species described worldwide. Periscelis Loew is the only genus known from
North America, with three extant species: Periscelis wheeleri is
the only species known from British Columbia. There is a second BC species of Periscelis that may be undescribed, occurring in collections of BC
ASTEIIDAE (Asteiid Flies ) [Fig. 90]
Asteiids are very small,
delicate and rarely collected flies, 1.0 to 2.5 mm long. Head normally higher
than long, with face concave. Frons broad and compound eyes large and bare.
Frons with one or two pairs of bristles. Ocelli present, and ocellar bristles
short or seta-like, divergent or proclinate. Post ocellar bristles weak or
absent. Oval vibrissae are well developed, but pale and inconspicuous. Antennae
short and decumbent, the arista with alternating short and long setae, giving
the arista a characteristic zigzag appearance. Thoracic scutellum with two pairs
of marginal bristles, the basal pair of bristles often seta-like, but the
posterior bristles are well developed and obvious. Legs are short and slender,
with tibiae lacking preapical dorsal bristles. The wings are long, hyaline and
unspotted. The costa is without a subcostal and without a humeral break, and the
subcostal vein is incomplete, not reaching the costa. R1 joins the
costa in the basal third of the wing, R4+5 and M are distinctly
convergent distally, and CuA2 and A1 are atrophied. The
abdomen is narrow, rather membranous and at most weakly sclerotized.
Little is known about the
biology and life cycle of these flies. Adults have been collected on windows and
at bleeding wounds on trees or fungi. Elsewhere in the world, adults have been
reared from fungi, and plant parts or remains.
Worldwide there are about
100 species in 11 genera. Five genera with 18 species are known from the Nearctic.
There are 2 genera and 4 described species known to occur in BC based on the
published literature and from collections of BC Diptera. Two of the most common
BC species are Asteia beata Aldrich and A. multipunctata Sabrosky.
Family CARNIDAE (Carnid Flies) [Fig. 91]
Small flies, 1.0 to 3.0 mm
long, and more or less shining black. Face of head rather concave, and frons
with at least two orbital bristles. Ocellar bristles strong, and postocellar
bristles subparallel. The gena has a row of strong bristles in the middle.
Vibrissae are present and strong, and there is a row of strong subvibrissal
bristles. The antennae often lie in a deep antennal groove. The proboscis has a
bulbous base and short inconspicuous labella. The thoracic scutellum is armed
with four short bristles, and the propleura are bare. The legs are slender, and
tibia lack a preapical dorsal bristle. Wings when fully developed are hyaline,
and the costa has both a humeral and subcostal break, while the subcosta is
complete although weak and faint distally. Vein R2+3 is typically
bisinuate. In the genus Carnus Nitzcsch the wings are usually broken off,
leaving merely a short stub. The abdomen normally well developed, but in Carnus, it is rather inflated, lacks sterna, and the membranes have
numerous setiferous sclerotized spots in females.
Most species are
saprophagous, and associated with carrion or excrement, with many having been
reared from bird’s nests. The Holarctic Carnus hemipterus Nitzcsch occurs
in bird’s nests and adults are often found on nestlings and may feed on blood.
The genus Carnus was reviewed by Grimaldi, 1997.
This is mostly a Holarctic
family, with over 40 described species. Three genera occur in North America,
with 16 described species. Fifteen species occur in Canada. Carnus
hemipterus, as well as at least five species of Meoneura including M. flavifacies Collin and M. triangularis Collin are reported from
Grimaldi, D. 1997. The
bird flies, genus Carnus: species revision, generic relationships, and a
fossil Meoneura in Amber (Diptera: Carnidae). American Museum Novitates
Family TETHINIDAE (Tethinid Flies) [Fig. 92]
Tethinids are small stocky
flies, 1.5 to 3.0 mm long, coloured yellow, grey or black and usually strongly
pruinose. The head is usually higher than long; the frons and face are strongly
to weakly narrowed in front; the face has a weak depression below each antenna
and has a slight median ridge. Ocellar bristles, inner and outer vertical bristles
and 1 to 5 orbital bristles are strong (the latter curve backward or laterally);
postocellar bristles are absent; inner occipital bristles are variable in size
and convergent. The lower edge of the head below the compound eye bears a row
of weak to strong setae; the foremost are vibrissa-like. The short antennae
usually droop; the third segment is almost circular; the arista bears extremely
short setulae. The scutum has one presutural and three postsutural dorsocentral
bristles. The scutellum is rounded, about twice as broad as long, without setae,
but with two pairs of marginal bristles. The wings are clear or sometimes slightly
white or brown; rarely with brown clouds on the crossveins. The anal angle and
alula are well-developed. The costa has no spines and is broken only at the
end of the subcosta. The subcosta is complete or sometimes fused with vein R1 near its tip. Veins R2+3, R4+5 and M1 typically
rather straight and more or less parallel to the long axis of the wing. Cell
cup is present, but small. The legs are slender, the femora sometimes
slightly swollen. The coxae and femora bear a few weak bristles; the mid- and
hind tibiae usually have an apical bristle below.
Most tethinid flies live
along ocean beaches or near alkaline ponds and lakes in more interior regions.
The larval biology is poorly known, although the larvae probably live in the
soil or in masses of algae or seaweed. Some species in the southern hemisphere
may be associated with seabird colonies.
The Tethinidae is a cosmopolitan
family occurring on all the main continents and many oceanic islands. It is
a nonspeciose group, with about 120 described species in 14 genera, although
many other undescribed species likely exist. In North America, 26 species are
described in five genera and at least five species in four genera occur in BC
based on published reports and collections of BC Diptera. Neopelomyia rostrata (Hendel) lives on the beaches of the Pacific Ocean from southern BC to California. Pelomyiella melanderi (Sturtevant) is also western, but occurs around
alkaline lakes in central BC south to California, Arizona and Mexico in both
inland and coastal habitats. In the west, including BC, P. mallochi (Sturtevant) is a widespread inland species, but it lives on sea beaches in
the eastern Arctic and along the Atlantic coast. The genus Tethina may
also occur on the province’s south coast beaches, but it has yet to be recorded
in the literature from the province. T. horripilans (Melander),
recorded as far north as Washington, is the most likely species to show up in
Family MILICHIIDAE (Milichiid Flies) (Fig. 93)
Milichiids are physically
small, 1-7 mm long, acalyptrate flies, often largely brown or black,
occasionally orange or yellow. Males of some genera with silvery pollinosity on
abdomen. Milichiids usually have two or three pairs of medioclinate frontal
bristles, and two or three pairs of lateroclinate to proclinate orbital
bristles; rarely with many reclinate frontal and orbital setae in an
indistinguishable series. Frons usually with two rows of interfrontal setae,
sometimes on distinctly shining stripes; lunule often with one or two pairs of
setulae; proboscis often elongate, geniculate. Wing with humeral and subcostal
break; the region of latter is often modified into a costal lappet; cell
cup closed, small. Milichiids are generally recognizable based on the
head bristling, humeral and subcostal breaks and the closure of cell
Although the biology of
the majority of species is unknown, many milichiids have general saprophagous or
coprophagous larvae, developing in decaying matter ranging from rotting fish and
animal dung to rotting plant material. In addition to these more mundane
lifestyles, larvae of many milichiids have a close association with Hymenoptera.
In the Nearctic, larvae of the genus Eusiphona have been found feeding on
the pollen in megachilid bee nests, this habit may hold true for Eusiphona mira Coquillett in BC. Some Phyllomyza species
have been found in association with formicine and ponerine ants in the
Palearctic and Oriental Regions; these groups of ants may also be hosts of Phyllomyza species in BC. Two Nearctic species of Pholeomyia have
been recorded from the refuse heaps in leaf-cutting ant nests. Neither of these
species of Pholeomyia nor the hosts occur in British Columbia.
Species in the genera Pholeomyia, Milichiella, Leptometopa, and Phyllomyza are known from caves and in association with bat guano, and may occur in similar
habits in BC. Many adult milichiid flies including the genera: Phyllomyza, Desmometopa, Neophyllomyza, Paramyia, Milichiella, and Leptometopa, all of which occur in British
Columbia, have species with adults that are kleptoparasitic on a wide range of
predaceous arthropods, such as spiders, assassin bugs and robber flies. Often
the kleptoparasitic milichiids will ride around on their hosts and feed on their
hosts’ partially digested prey. The vast majority of milichiid specimens
collected as kleptoparasites of spiders are female and it is suspected that the
extra protein from kleptoparasitic meals may be necessary for egg maturation.
Although Leptometopa latipes (Meigen) is documented as a spider
kleptoparasite, the larvae are also commonly associated with bird nests,
including records from bird nests in BC. Adults of species in several genera
(Desmometopa, Leptometopa, Neophyllomyza, Paramyia, Milichiella, and Pholeomyia) have been collected at flowers. Like
the cases of kleptoparasitism most specimens found at flowers are female, there
appears to be no oviposition on the plants and it is thought that the flies may
be receiving nutrition essential for egg maturation. Adult male milichiids have
equally well documented unique behaviors. Males of some species of Milichiella, and Pholeomyia have silvery abdomens and form mating
swarms that can be seen from long distances.
Worldwide there are about
20 described genera and 275 described species, of which 12 genera and 39 species
occur in the Nearctic region. The genera Paramyia, Phyllomyza, Madiza, Desmometopa, and Pholeomyia each have one described
species recorded in British Columbia while the genus Leptometopa has
two described species recorded from BC, for a total of seven described species.
There are several other described widespread species of the genera Desmometopa, Eusiphona, and Milichiella that occur in BC collections in Canadian
entomological museums, but are unpublished records. As well, there are numerous
undescribed species of Neophyllomyza, and Phyllomyza in British
Columbia awaiting formal description.
Family CHLOROPIDAE (Frit Flies, Grass Flies) [Fig. 94]
Frit flies are minute to
small, 1.5 to 5.0 mm long; with the number and size of the body bristles clearly
reduced. The body is black, grey, black and yellow, or black and red. The frons
is broad, usually with the ocellar triangle well-developed, plate-like, clearly
demarcated, shining to pruinose and normally with a single row of setae-bearing
punctures along the lateral margins. The frons usually projects only slightly
and the face is normally somewhat concave with the vibrissal angle rounded.
The third antennal segment is usually round, sometimes kidney-shaped or elongate
and bearing an arista that is normally pubescent or sometimes setulose, but
rarely is bare. The head bristles are usually short and weak; the inner and
outer verticals, ocellars and postocellars are commonly present. The latter
bristles are parallel, convergent or crossed. The fronto-orbitals are usually
represented by short setae curving rearward. Vibrissae, when present, are usually
fine and setulose. The scutum is normally longer than broad, with fine setulae
set in distinct rows and frequently with coarse, setulae-bearing punctures;
one posterior dorsocentral bristle almost always occurs. The scutellum sometimes
has marginal tubercles bearing bristles. The proleuron is sharply ridged in
front. The wings are rarely absent or reduced and normally lack any colour pattern.
The costa has a subcostal break; the subcosta is incomplete, usually faint.
Veins R4+5 and M1+2 are long, the former ending before
the wing tip, the latter ending behind the tip. Cells b-m and d-m are completely
joined, forming a single long cell; CuA1 often has a characteristic
jog near the middle of cell bm+dm. Vein A1 and cell cup are
always missing; the anal area of the wing is usually broadly rounded. Normally
the legs are short, slender, and without bristles, except an apical or subapical
spur sometimes occurs on the middle or hind tibia. Many species have an elongate
oval tibial organ on the upper surface of the hind tibia. The abdomen is broad,
tapers to the tip, and each segment in front of the terminalia is about equal
The larvae of many species
of frit flies develop in grass stems, shoots, and decaying plant matter. A few
species damage crops; one of the best known is the Frit Fly, Oscinella
frit (Linnaeus), so-called because the wheat it damaged was termed "frits"
by Swedish farmers. It also attacks rye, barley, lawn grasses and corn. The
Wheat Stem Maggot, Meromyza americana Fitch, is also destructive. Some
species produce galls; the European Lipara lucens Meigen forms galls on
the giant marsh grass, Phragmites. Predaceous chloropids include: Thaumatomyia glabra (Meigen) which preys on root aphids, and the larvae
of Pseudogaurax Malloch which feed on egg masses of spiders, tussock
moths and mantids. Adult chloropids are most common in grass and sedge habitats.
Some are found on flowers and a few, especially in the genus Hippelates Loew, are bothersome and even transmit disease by hovering around sweating faces
and sipping liquid secretions from eyes, sores and wounds. Pseudogaurax and Hippelates are not known from BC.
The family Chloropidae ranges
around the world, with over 2000 described species in more than 160 genera;
over 50 genera containing about 290 species occur in North America. In BC there
are at least 14 genera and over 30 described species. There are two prominent
subfamilies in BC -- members of the Oscinellinae are usually black bodied while
those of the Chloropinae are yellow or red, marked with red to black stripes.
The latter subfamily contains Thaumatomyia Zenker, one of the most speciose
genera in the province with at least five species recorded. T. glabra is Holarctic and common over all of North America; its larvae prey on various
root aphids including the economically damaging sugarbeet root aphis (Pemphigus
populivenae Fitch). There are only two species of Chlorops Meigen
recorded in BC, although probably more occur in the province; the species are
usually yellow with black stripes. C. certimus Adams ranges over
much of the continent; C. stigmatus Becker is confined to the
mountains of the Northwest. Meromyza Meigen contains the Wheat Stem Maggot, M. americana Fitch, which apparently is not known in BC. But the
Holarctic M. pratorum Meigen and M. saltatrix (Linnaeus)
are recorded; the former is boreal, the latter cordilleran. In the Oscinellinae, Elachiptera Macquart has at least two species occuring in BC including E. decipiens (Loew) which is widespread. The Frit Fly, Oscinella
frit (Linnaeus) and O. nitidissima (Meigen) are Holarctic
and also are known from BC. Other BC genera include Olcella Enderlein, Tricimba Lioy, Lasiosina Becker and Malloewa Sabrosky.
SCATHOPHAGIDAE (Dung Flies) [Fig. 48]
Scathophagids are slender,
small to medium-sized flies (about 3 to 11 mm long); bristling ranges from weak
to strong and some species are densely setulose. The ground colour is usually
black, brown or yellow, but some are strikingly bicoloured; some are densely
grey or yellow pruinose. The head is normally higher than long, with the frons
of equal width in males and females. There are 1 to 3 orbital bristles and 1
to 6 frontal bristles; the latter are curved inward. Also present are ocellar,
postocellar and inner and outer vertical bristles. The parafacial area is bare;
the vibrissa is weak or strong and there are few to many weaker bristles and
setulae nearby. The compound eyes are bare. The second antennal segment has
a distinct seam above; the third segment is two to five times longer than wide,
usually rounded at the tip and sometimes with a long bristle near the base of
the arista. The arista is three-segmented, straight or rarely elbowed, and bare
or feathery. The bristles of the thorax are normally rather strong, but those
on the disc of the scutum are sometimes short and setae-like. The postpronotum
usually has one or two bristles; there are normally two presutural and three
postsutural dorsocentral bristles. The scutellum rarely has more than two pairs
of marginal bristles. The wing venation is rather constant; the costa has costagial,
humeral and subcostal breaks, the subcosta is complete and vein R1 joins the costa before the middle of the wing. Vein R4+5 meets the
costa at about the wing tip and the costa ends at vein M1. Vein A1 is usually complete, but sometimes ends before the wing margin. The wings are
normally clear, but sometimes spots or bands occur. The legs are slender; bristles
vary from weak to strong. The front femur and tibia sometimes bear short black
setae below and are sometimes highly modified in males. The abdomen is slender,
but in males is frequently enlarged at the tip; the first and second tergites
Only some species of dung
flies develop in dung. Larvae of the large and common genus Scathophaga Meigen mostly do so, although some larvae feed in rotting seaweed on ocean beaches.
Other Scathophaginae feed in a wide range of plants, especially monocots including Scirpus Linneaus and Juncus Linneaus. Still others are predators
in water, wet soil or plant tissues. Larvae of the subfamily Delininae mine
in the leaves of plants in the lily and orchid families. Adults prey on insects
and other small invertebrates.
The Family Scathophagidae
has often been treated as part of the Anthomyiidae or Muscidae. Its approximately
260 named species are almost completely restricted to the Holarctic region --
about 35% of North American species also occur in the Old World and only about
five species are known south of the equator. There are 37 genera and about 150
described species known from the Nearctic. It is, in general, the most northerly
distributed of any fly family; about 25 North American species are confined
to the arctic tundra. There are about 23 genera and 50 described species known
to occur in BC based on published records and collections of BC Diptera. The
most speciose genera in BC are Cordilura Fallén (12 species) and Scatophaga Meigen (10 species) in the Scathophaginae. In North America
these genera have 42 and 29 species respectively. Cordilura confusa Loew, C. fuscipes Zetterstedt, C. gracilipes Loew
and C. latifrons Loew are all boreal species and common in most
of BC. The most familiar species of Scathophaga is S. stercoraria (Linnaeus), a large, golden species common around dung everywhere; it can be
abundant in seabird colonies. S. furcata (Say) is also Holarctic
and widespread. S. frigida Coquillett and S. intermedia Walker are common seabeach species. Other examples of BC species in the subfamily
include Brooksiella varicornis (Curran), Chaetosa punctipes (Meigen), Gimnomera tibialis (Malloch), Megaphthalma pallida (Fallen), Megaphthalmoides unilineata (Zetterstedt), Microprosopa diversipes Curran and Pogonota gilvipes (Loew). The subfamily
Delininae is represented in BC by at least six genera; of which five only have
one species known from BC -- Parallelomma vittatum (Meigen), Delina nigrita (Fallén) and Hexamitocera loxocerata (Fallén)
are Holarctic and boreal; Synchysa tricincta (Loew) is boreal
and Peratomyia vittata (Coquillett) is western in distribution.
In BC the genus Nanna contains at least three species including N.
pallidipes (Malloch) and N. similis (Coquillett) which range transcontinentally
in the boreal forest.
ANTHOMYIIDAE (Root-Maggot Flies) [Fig. 49]
Anthomyiids are small
to medium-sized flies (2 to 12 mm long), usually yellow, brown, grey or black
and without any metallic sheen. The compound eyes are usually well-separated
in females, often meeting above in males; they are bare to densely pilose. The
frons bears frontal, vertical and ocellar bristles; flies with separated compound
eyes normally also have orbital bristles. Vibrissae are present. The antenna
has a quadrate or oblong third segment and the arista is bare to plumose. The
scutum normally has paired postsutural acrostichal bristles, one or two pairs
of presutural dorsocentral bristles and one to four pairs of postsutural dorsocentrals.
There are always two notopleural bristles. The scutellum has a pair of basal
and a pair of apical bristles; there are normally setulae on the underside.
The costa reaches the tip of vein M1. Cell r4+5 is broadly
open at the wingtip and vein A1 is usually traceable to the wing
margin. The legs are slender and bristly. The base of the first segment of the
hind tarsus bears a strong bristle underneath. The abdomen is usually cylindrical
and more or less conical. Sternite 5 in males is bilobed; the female ovipositor
is usually tubular.
Adult root-maggot flies
can be common on flowers; the larvae mostly feed in the roots, stems, leaves
and flowers of living or decaying plants. The nonspeciose subfamily Fucelliinae
contains marine beach species whose larvae feed on seaweed washed ashore; adults
swarm in large numbers around these piles of wrack. The rest of the family comprises
the subfamily Anthomyiinae, a diverse group living in many varied habitats.
The most obviously economically important species are pests attacking crops. Pegomya hyoscyami (Panzer) (Spinach Leaf Miner), Delia antiqua (Meigen) (Onion Maggot), D. platura (Meigen) (Seed Corn Maggot) and D.
radicum (Linnaeus) (Cabbage or Radish Maggot = Hylemya brassicae (Bouché)) are introduced European species now widespread across the northern
temperate regions. Other species attack many cultivated plants. Many more species,
however, are certainly important in pollination and in the recycling of organic
matter. Some are scavengers living on the dung of mammals and birds, others
are parasites or inquilines in the burrows of tortoises and rodents, and species
of Leucophora Robineau-Desvoidy live in the nests of solitary bees and
wasps, especially in dry, sandy habitats. Many species, such as some Hydrophoria Robineau-Desvoidy, are common in and around wetlands of all sorts and some larvae
are aquatic. Still others breed in the fungi of forests and meadows.
The Family Anthomyiidae
is cosmopolitan in distribution, but is especially diverse in the Holarctic
region. The family often has been treated as a subfamily of the Muscidae and
many authors include the Scathophagidae as a subfamily within the Anthomyiidae.
There are 41 genera and over 700 described species in the Nearctic of which
30 genera and over 200 species are recorded in BC. The subfamily Fucelliinae
(19 North American species) is represented in BC by several species of Fucellia along Pacific beaches, including F. separata Stein which is common on
the sand beaches of western Vancouver Island. The Anthomyiinae contains a number
of diverse genera in BC -- Delia Robineau-Desvoidy (77 species recorded
in the province), Pegomya Robineau-Desvoidy (23 species), Zaphne Robineau-Desvoidy (14 species), and Lasiomma Stein (12 species) are among
the most speciose. The principal introduced pests of vegetables are common in
BC -- Pegomya hyoscyami (Panzer), Delia antiqua (Meigen), D.
platura (Meigen) and D. radicum (Linnaeus). Strobilomyia neanthracina Michelsen, the Spiral Spruce-cone Borer, damages the seeds of White Spruce in
northern and central BC, causing considerable losses in seed crops in some years. Pegomyia bicolor (Wiedemann) is a Holarctic species that ranges over
most of North America; it mines in the leaves of species of Rumex Linneaus. P. carduorum Huckett larvae mine in Cirsium P.Mill. (thistles). Anthomyia pluvialis (Linnaeus) is a widespread Holarctic species; the
top of the thorax is pale grey marked with large dark spots. The larvae have
been found in birds’ nests. Nine species of Leucophora, bee and wasp
parasites, are recorded in BC; these include L .cinerea Robineau-Desvoidy,
a Holarctic species of the western mountains and the boreal L. maculata (Stein).
MUSCIDAE (Muscid Flies) [Fig. 50]
Muscid flies are slender
to stocky, 2 to 14 mm long and usually bristly. Their colour ranges from yellow
to grey or black, but some are metallic blue or green. In a few cases the flies
are brightly setulose. The wings are usually unmarked, but some have clouded
crossveins. The head is usually higher than long with the frons in males narrow
to broad and its central plate sometimes strongly reduced; the frons in females
is at least 25% as wide as the head with the central plate always distinct and
normally wider than the fronto-orbital area. There are one to many frontal bristles
curved inwards. The parafacial area is usually bare, but the vibrissa is normally
strong and has associated bristles or setulae. The face is usually flat or concave,
rarely with a medial ridge or tubercle on the upper part. The third antennal
segment is at least twice as long as broad and usually rounded at the tip; the
arista is 3-segmented, bare to plumose or rarely comb-shaped. The thoracic bristles
are usually long and prominent; there are normally 1 to 2 presutural and 3 to
4 postsutural dorsocentral bristles. The scutellum usually bears two pairs of
marginal bristles; there is rarely an isolated group of setulae on the underside
of the apex. The costa has costagial, humeral and subcostal breaks; the costa
usually ends where vein M1 meets the margin. Vein M1 is
more or less parallel to vein R4+5 or is bent forward; vein A1 never reaches the wing margin. The legs are usually slender with varied bristling;
the base of the first tarsal segment of the hindleg lacks the distinctive ventral
bristle characteristic of most anthomyiids. Both sexes have five exposed abdominal
tergites usually bearing strong marginal bristles.
Larvae develop in many
habitats, from dung and decaying plant matter to carrion and fungi. They are
found in the nests of bees, wasps, birds, mammals and other animals. Others
live in fresh water or soil of many sorts; a very few develop in living plant
tissue. Most evidently feed on excrement, decaying organic matter and the micro-organisms
that inhabit this material; some are known as predators of insect larvae or
other invertebrates. A few species such as Fannia canicularis (Linnaeus) (Lesser House Fly) and F. scalaris (Fallén)
(Latrine Fly) can invade the human body and cause intestinal and other myiasis.
The food of adults is also varied. They feed on dung or decaying organic matter,
plant sap, honeydew and pollen. Some are predators of insects; others suck vertebrate
blood or feed on the exudates of mammals and other animals. Those species that
feed on human feces and food, such as Musca domestica Linnaeus (House
Fly) can spread human diseases such as typhoid fever, cholera and dysentery.
Muscid flies are widespread
around the world, occurring on all continents and most oceanic islands. To conform
to the generic level keys in the Manual of Nearctic Diptera we have maintained
the broad definition of the family. Often now the subfamily Fanniinae is considered
to be a separate family (Fanniidae). About 4300 species in about 180 genera
are described with 4 genera and about 270 described species of those in the
Fanniinae and the rest in the Muscidae in the strict sense. Many species live
on the arctic tundra and about one quarter of the Nearctic species, especially
the northern ranging ones, are naturally Holarctic in distribution. Fifty-three
genera and 727 described species (of which 4 genera and 113 species are in the
Fanniinae) occur in the Nearctic and 34 genera and about 210 species are recorded
in BC. Of these BC records, 4 genera and 57 species are in the Fanninnae. The
genus Fannia Robineau-Desvoidy itself is the most diverse muscid genus
in the province, with 53 known species, about half the North American Fannia fauna. The most familiar species of the genus is F. canicularis (Linneaus);
it is closely associated with humans, although it is less dependent on human
habitations than is Musca domestica Linneaus (the House Fly). It often
replaces the latter species around houses in subarctic regions. As in other
species of Fannia, the males hover in small swarms near the lower branches
of trees; F. canicularis males also fly in circles under ceiling fixtures
in houses. Although it is most commonly found breeding in excrement and decaying
garbage around human dwellings, this species also breeds in bird and rodent
nests and wasp and bumblebee colonies. Other Fannia species in the province
develop in such habitats, too, but most commonly the genus breeds in mushrooms,
leaf litter, decaying vegetation and animal carcasses.
Other speciose muscid
genera in BC include Spilogona Schnabl (25 species), Coenosia Meigen (20 species), Helina Robineau-Desvoidy (27 species) and Hydrotaea Robineau-Desvoidy (16 species). Hydrotaea species, especially
males, have a distinctive hovering and soaring flight; some species, in BC including H. armipes (Fallén), H. meteorica (Linnaeus) and H.
scambus (Zetterstedt) annoy people by landing on them and feeding on perspiration
and the secretions of the eyes, nose and mouth. H. armipes also often
feeds from wounds on large mammals cause by horse fly bites. Hydrotaea leucostoma (Wiedemann), the so-called Dump Fly, can be common in urban areas; it breeds
in garbage and dung and preys on housefly larvae in such habitats. Adults of
the genus Lispe Latreille are predators of other insects and fly actively
near water, often perching on rocks in streams. There are at least four species
in BC; L. tentaculata (De Geer) is Holarctic and transcontinental in
distribution while L. salina Aldrich is western. Phaonia has at
least 8 described species in BC. Phaonia pallidosa Huckett is all orange while P. caerulescens (Stein) is metallic blue-black and superficially
resembles a blow fly; both range from BC to California. The Holarctic and common Neomyia cornicina (Fabricius) is a striking, bright metallic green muscid
that, at first glance, also can be mistaken for a calliphorid. Its larvae, an
unusual blue colour, live mostly in cow dung. Mesembrina latreillii Robineau-Desvoidy
is an easily recognized muscid, 10 to 12 mm long, metallic black and with bright
yellow-orange wing bases. Its close relative, M. solitaria Knab also
has golden wing bases, but is notable for its dense and colourful body setulae
-- mostly golden on the top of the thorax and the rear half of the abdomen,
black underneath and at the abdomen base. The former species ranges across the
northern parts of the northern hemisphere, but the latter is restricted to North
America; both develop in dung.
Musca domestica is the notorious House Fly, common now over much of the earth and certainly
widespread in BC. Musca autumnalis De Geer is a European immigrant, first
recorded in North America in 1952; it prefers moist shady pastureland and breeds
in cow dung, which the House Fly avoids. Called the Face Fly because it commonly
feeds on fluids from the eyes and nostrils of cattle, M. autumnalis frequently
gains notice for its habit of overwintering in buildings. Muscina stabulans (Fallén), which occurs throughout the province, acts a bit like a calliphorid
fly, often entering houses and laying eggs in fresh or cooked meat. It can be
a parasite of insect pupae and of nestling birds and is known to cause intestinal
myiasis in humans. Several muscids suck the blood of vertebrates. In BC the
main culprit is Stomoxys calcitrans (Linnaeus), the Stable Fly, a cosmopolitan
pest that lays its eggs in mouldy hay bales and rotting vegetation of various
sorts; it is a fierce biter of cattle and people. The other common biting muscid
in BC is Haematobia irritans (Linnaeus), a common range species that
breeds in cattle dung and feeds on the blood of these animals. Because the flies
often rest at the base of the hosts’ horns, the species has been dubbed the
(Blow Flies) [Fig. 51]
Most species of blow flies
are stocky, medium-sized to large, 4.0 to 16 mm long, with bodies partly or
completely metallic blue, green, black or brassy. Less frequently, they are
small, slender and without metallic coloration. The sexes often differ distinctly
in colour. The head is distinctly higher than long and the compound eyes in
males rarely meet above, although the frons is narrower than in females. The
lunule is bare and shining; the frontal setae reach forward to the second antennal
segment; the frons usually is finely setulose. The vibrissa is strong and the
gena is thickly setulose. Females have one backward-curving orbital bristle
above and two forward-curving ones below. Ales lack frontal and outer vertical
setae. The antenna has the arista long plumose on at least the basal two-thirds.
Thorax with two notopleural setae; usually two or three anterior and posterior
dorsocentral bristles are present. The scutellum has one to three pars of lateral
bristles; the apical pair is usually strong. The subscutellum is weakly developed
or absent. The wing has the bend of vein M right-angled or acute; cell r4+5 is almost always open at the wing margin.
Blow flies are predominantly
flesh-eaters as larvae. The most familiar blow flies, the common species called
bluebottles and greenbottles, lay eggs on carcasses of all kinds and also are
attracted to fresh and cooked meats and dairy products indoors. The restless
flying around in rooms, so commonly seen, is mainly a search for places to lay
eggs. The term "blown" refers to meat that has had blow fly eggs laid
on it. The development of some species, such as Phormia regina (Meigen)
and various species of Calliphora Robineau-Desvoidy, on human
corpses is frequently monitored in establishing the time of death in murder
cases. Some species are also attracted to excrement and can transmit digestive
system pathogens. Most economically important are those species whose larvae
are called screwworms (Lucilia Robineau-Desvoidy, Phormia Robineau-Desvoidy, Protophormia Townsend, Cochliomyia Townsend, and others). Eggs are
laid in body orifices, on wounds or soiled hair and wool, especially on domestic
animals. Cattle and sheep are particularly vulnerable and significant mortality
can occur. Some species of Lucilia also attack amphibians, with often
deadly results. The larvae of Protocalliphora Hough and Trypocalliphora Peus suck the blood of nestling birds of a huge range of species from eagles
and owls to swallows, bluebirds, warblers and sparrows; these parasites can
be troublesome in nest boxes. Species of Pollenia Robineau-Desvoidy (cluster
flies) often overwinter in the attics and outer walls of houses and other such
places; large numbers often get trapped in the spring when they try to escape
to the outside. Females lay eggs in the soil and the larvae attack earthworms.
Some genera, such as Angioneura Brauer & Bergenstamm, are internal
parasites of land snails. Adult blow flies visit flowers or rest on foliage,
usually in the sun and, when attracted to carrion nearby, their buzzing can
be loud and noticeable. Many calliphorids are easy to rear and some species
are regularly used in laboratories studying insect physiology and other aspects
of insect biology.
The Family Calliphoridae
ranges worldwide, with about 1000 described species in 150 genera. About 80%
of the species are from the Old World; Africa is especially diverse. There are
only 17 genera and about 95 species known in North America, although there has
been much lumping of species and genera. There are 11 genera and about 35 species
known to occur in BC based on published records and collections of BC Diptera.
About seven species of Calliphora are known in BC. The European C.
vicina Robineau-Desvoidy and C. vomitoria (Linnaeus) are now widespread
in many parts of the world and are common around many BC homes; C. terraenovae Macquart and C. lilaea (Walker) are found over much of North America,
as is Cynomya cadaverina (Robineau-Desvoidy). The five species of Lucilia in the province are of two groups: the Holarctic L. silvarum (Meigen)
and the western North American L. elongata (Shannon) and L. thatuna (Shannon) attack frogs and toads; the Holarctic L. illustris (Meigen)
and the now cosmopolitan L. sericata (Meigen) are the well known greenbottles
that breed in carrion and excrement, sores and wounds. Phormia regina (Meigen) is a very common fly around the temperate parts of the northern hemisphere;
the dark green-black fly is abundant around carrion and corpses and is a frequent
invader of living flesh in animals. Protophormia terraenovae (Robineau-Desvoidy)
is widespread across the continent, but is especially abundant in the North
where it is a pest of caribou. Pollenia rudis (Fabricius) is the most
abundant cluster fly in BC, most obvious in early spring when it basks on the
sunny sides of buildings. Fourteen of the 25 species of Nearctic Protocalliphora species develop in birds nests in BC. Trypocalliphora braueri (Hendel),
widespread in BC on a great range of bird species, should probably be maintained
in Protocalliphora. The latter species and P. cuprina (Hall), P. halli Sabrosky, Bennett and Whitworth and P. hirundo Shannon
and Dobroscky were all found in Barn Swallow nests in a colony at Qualicum Beach. P. chrysorrhoea (Meigen) is known from northern BC only; apparently it
is restricted to the tunnel nests of Bank Swallows. P. sialia Shannon
and Dobroscky is common in nest boxes used by bluebirds and swallows, but also
attacks many other species.
Family OESTRIDAE (Bot and Warble Flies) [Fig. 52]
The Family Oestridae contains
medium-sized to large (9 to 25 mm long) flies with stout, bristleless, but often
thickly setulose bodies. They often resemble bumble or carpenter bees. The head
is broad, higher than wide in side view and the flat face is either broad and
shield-shaped or strongly narrowed below the antennae. The antennae are small
and sunk deeply into pits; the third segment is globular and bears an arista.
The arista is either slender and bare with a thickened base or, in Cuterebra Clark, feather-like and lacking the broad base. The mouthparts are small and
compact, or often atrophied. The thorax is covered in short setulae or is densely
long-setulose; rarely there are some weak bristles present. The legs are short,
stocky and setulose; the femora and tibiae often bear some weak bristles and
the tips of the tibiae and the tarsal segments usually have short, spine-like
bristles. Wings with vein M highly variable -- straight or weakly curved, ending
at the wing margin well behind the wing tip, or curving forward to join vein
R4+5 just before the wing margin, or meeting the wing margin immediately
behind the tip of vein R4+5, or strongly angled with a prominent
stump vein beyond crossvein dm-cu. The abdomen is globose to conical with shiny
cuticle and long, coloured setulae or is partly or completely pruinose.
The species of the Family
Oestridae are obligate parasites of mammals and most are strongly host-specific.
Adults have tiny or atrophied mouthparts and apparently do not feed on sugars
or protein as do other calyptrate flies. They rely on fat reserves for energy,
although some species of Cephenemyia Latreille and Cuterebra evidently
drink fluids by pressing the underside of the head against a damp substrate.
In the subfamily Cuterebrinae the eggs are usually laid in places frequented
by the host mammals and the larva enters the host through any orifice, eventually
migrating to subcutaneous tissues where it feeds in the warble, a pouch formed
in the connective tissue of the skin. The larva breathes through the posterior
spiracles, which communicate with the outside air through a small hole in the
skin. The position of the warble is often predictable; those of Cuterebra in mice and chipmunks are usually on the belly while those in rabbits are normally
on the neck. When mature the larva drops from the host and pupates in the soil.
Females of Dermatobia hominis Linnaeus Jr., which attacks a wide range
of hosts (including humans) in the Neotropics, first catches a blood-sucking
fly (such as a mosquito), on which she lays her eggs and then releases. When
the fly lands on a host to bite, the eggs hatch and the larvae burrow into the
Most species of the Subfamily
Gasterophilinae lay eggs on hairs around the mouth or on the legs of the host
– horses, zebras, elephants and rhinoceroses. The eggs hatch spontaneously or
when licked, and the larvae feed in the mouth before moving to the stomach or
intestines, where they complete development. In the Hypodermatinae, which attack
rodents, lagomorphs and ungulates, eggs are placed on hairs of the host’s legs
or flanks. The larvae of Hypoderma Latreille burrow into the skin, migrate
through the body by varoius routes to the skin of the back where warbles are
formed. Larvae of the Oestrinae live in the respiratory passages of a wide range
of hosts including ungulates, horses, elephants and kangaroos. The eggs are
retained in the female until they hatch; the young larvae are expelled within
droplets of fluid onto the face of the host. In some Cephenemyia, at
least, the larvae crawl into the mouth and enter the sinuses and throat via
the palate. Bot fly larvae feed on blood and mucous and can cause severe damage
to the tissues; mature larvae are coughed out of the mouth or sneezed out of
the nostrils. The Sheep Nostril Fly or Sheep Bot Fly, Oestris ovis Linnaeus,
infests the noses, sinuses and throats of domestic sheep, but evidently has
not transferred to native species. It also will attack goats, dogs and, sometimes,
even humans. There are some cases of larvae living in the human eye where they
can damage the cornea, but apparently there they are unable to develop past
the first instar.
The Family Oestridae, containing
over 150 species in 28 genera, is widespread on all the major continents, but
is most diverse in Africa and central Asia. The African Elephant alone supports
five species. Although all the subfamilies except the Gasterophilinae have native
representatives, the fauna of North America is much poorer, with six genera
and 41 described species. The four subfamilies noted here sometimes have been
treated as separate families. The Subfamily Cuterebrinae contains flies whose
larvae form warbles under the skin of rodents, lagomorphs, monkeys, livestock
and humans. The unusual Dermatobia hominis is sometimes brought back
to BC as larvae, burrowed under the skin in various parts of the body, by unwitting
tourists who have spent time in tropical America. The largest genus in the subfamily,
and the family as a whole, is Cuterebra, with over 60 species that develop
in rodents and lagomorphs. Six species of these big blackish flies are recorded
in BC, including C. fasciata Swenk, which develops in squirrels
and chipmunks, and the widespread C. grisea Coquillett, a common
parasite of Peromyscus mice that ranges from BC to Nova Scotia south
to New Jersey and Utah.
The horse bots of the Subfamily
Gasterophilinae are Old World species, but three are now cosmopolitan, having
been introduced with the horse to many regions. Gasterophilus haemorrhoidalis (Linnaeus), G. intestinalis (De Geer) and G. nasalis (Linnaeus) all are recorded in the digestive tracts of BC horses. The subfamily
Hypodermatinae is represented in North America (and BC) by one native species,
the Holarctic Hypoderma tarandi (Linnaeus), which attacks caribou, and
the introduced and cosmopolitan H. bovis (Linnaeus) and H. lineatus (Villers), which are parasites of domestic cattle. The adults
of these flies are setulose and bee-like with the base of the abdomen having
black setulae and the apical half red setulae. The persistent attacks of H. bovis cause cattle to panic and stampede. In BC the Subfamily Oestrinae
contains three species: Oestrus ovis Linnaeus, a grey, black-spotted
fly introduced on domestic sheep; Cephenemyia apicata Bennett and Sabrosky,
ranging from BC and Alberta south to Montana and California on Mule Deer; and C. jellisoni Townsend distributed from BC to Ontario south to
Texas and California on Moose, Elk and Mule Deer.
(Flesh Flies) [Fig. 53]
Species of the family
Sarcophagidae are robust, mostly grey flies ranging from 2.5 to 23 mm long.
The thorax is usually has three dark stripes on top and the abdomen is striped,
banded or spotted with markings that shift tones depending on the angle of the
light. The abdomen is sometimes partly red. The head is wider than high and,
in side view, usually a little higher than long. The compound eyes are bare.
The fronto-orbital area usually has sparse setulae, but the central part of
the frons is normally bare. There about 4 to 10 frontal setae and one to three
orbital setae curving backward, two to four curving forward; these last setae
are usually missing in males in the Sarcophaginae. The face is concave and lacks
a central ridge. Vibrissae are present. The antennal arista is bare or finely
setulose (most Miltogramminae) to plumose, especially on the basal half or two-thirds
(most Sarcophaginae). On the thorax, there are normally 3 to 4 anterior and
3 to four posterior dorsocentral bristles. The scutellum has 2 to 3 pairs of
lateral setae and one pair of discal setae; if a pair of apical setae occurs,
they are small. The wing has the origin of vein R4+5 setulose above
and below, with the setulae continuing toward crossvein r-m above. Any extension
at the bend in vein M is usually not developed, but is merely present as a short,
Flesh flies lay larvae
or eggs that are ready to hatch. Larvae of the tribe Miltogramini in the subfamily
Miltograminae are deposited by adult females at the entrance to the nests of
burrowing solitary bees and wasps; the larvae feed on the provisions in the
cell and sometimes kill the host’s egg or larva. Eumacronychia attack
lizard and turtle eggs and Macronychia parasitize adult tabanid flies.
Species of the tribe Paramacronychiini (subfamily Miltograminae) and the subfamily
Sarcophaginae are obligate parasites or scavengers that become facultative parasites
in a wide variety of animals, mostly arthropods – Orthoptera, Coleoptera, Lepidoptera
and, to a lesser extent, Neuroptera, Hemiptera and Hymenoptera. Some attack
scorpions, spiders, myriapods and snails. Others can develop in excrement. A
few species are implicated in myiasis of the human flesh, but most are considered
secondary invaders of wounds and sores. The exception is species of the genus Wohlfahrtia Brauer & Bergenstamm (including the BC species) which
lay larvae on the skin of the young of healthy mammals, including human infants;
the larva breaks the skin and feeds subcutaneously. The association of the family
with humans is limited, however, and it has not gained the notoriety of the
blow flies or some muscids, such as the House Fly. A few species are economically
beneficial. Sarcophaga aldrichi Parker attacks the pupa of Malacosoma
disstria Hübner (Forest Tent Caterpillar) and is a major control agent
of this defoliating pest. Others are significant in the control of crop-damaging
grasshoppers. Adults feed at sources of nectar, sap and honeydew; males, especially,
often visit flowers. Males also often perch conspicuously on various surfaces
waiting for females to fly by.
There are over 2500 named
species of sarcophagids worldwide, placed in 108 genera. The number of genera
cited for the family depends mostly on how the speciose genus Sarcophaga Meigen is subdivided; in its broad sense, Sarcophaga contains
almost 800 known species. There are about 50 genera and 390 species described
in the Nearctic; with 22 genera and about 90 described species known for BC
from the published literature and collections of BC Diptera. Species of the
tribe Miltogrammini, that parasites and live as inquilines in bee and solitary
wasp nests, are comon in BC. There are eight genera with numerous species recorded
for BC with these habits. Amobia oculata Zetterstedt is Holarctic and
widespread in North America; it develops in nests of sphecid wasps such as Sceliphron Klug and Trypoxylon Latreille and eumenid wasps such as Symmorphus Wesmael, and Eumenes Latreille. At least three species of Metopia Meigen are recorded in the province; one, Metopia argyrocephala (Meigen),
which ranges over most of the continent as well as in Eurasia, attacks the underground
cells of Sphex Linneaus and the halictid bees of the genus Lasioglossum Curtis. Senotainia trilineata (Wulp) adults are often found on flowers;
at least some populations develop in the nests of Bembix digger wasps. Taxigramma hilarella (Zetterstedt) deposits larvae in the nests of ground-nesting
sphecid wasps where they feed on the noctuid moth caterpillars provisioning
In BC the subfamily Sarcophaginae
is predominantly represented by three genera – Sarcophaga Meigen (with
18 species known), Blaesoxipha Loew (with 25 species known) and Ravinia Robineau-Desvoidy (with 8 species known). Species of Ravinia mainly develop
in excrement. For example, the common and widespread R. lherminieri Robineau-Desvoidy
has been reared from cattle dung. Grasshoppers are the main targets of Blaesoxipha.
In BC, B. opifera (Coquillett), a western species, is one of the most
abundant flesh flies in the dry Interior, where it attacks species of Melanoplus Stål. Other species with the same hosts include B. aculeata (Aldrich), B. atlanis (Aldrich), B. falciformis Aldrich, B.
hunteri (Hough) and B. kellyi (Aldrich). The females of the latter
species strike grasshoppers in flight, depositing a larva under the open hindwing. Melanoplus sanguinipes (Fabricius) (Migratory Grasshopper), one of the
most common grasshoppers in the province, is attacked by at least 14 different
sarcophagid species. Species of Blaesoxipha parasitize insects other
than Orthoptera; for example, B. eleodis (Aldrich), a widespread western
fly, uses several species of the abundant tenebrionid beetle genus Eleodes Eschscholtz as hosts. Sarcophaga aldrichi Parker is common across
the forests of Canada and the United States where the forest tent caterpillar
is found; the fly sometimes occurs in outbreak numbers with its host and can
become a pest around forest campsites. It places its larva on the moth’s cocoon;
it also attacks spruce budworms. S. cooleyi Parker is a scavenger that
breeds in human excrement and much other garbage; the remains of fish are a
favourite source of larval food. S. sarracenioides Aldrich is known to
attack the huge wood-boring beetle, Ergates spiculatus LeConte, as is Helicobia rapax (Walker). Although it has been reared from a wide variety
of hosts, this latter flesh fly is probably the main parasite of Melanoplus
sanguinipes in BC.
(Tachinid Flies) [Fig. 54]
Tachinids are tiny to
large flies, often strongly and densely bristled. The head takes many shapes
– usually it is higher than long with a sloping frons and small antennae in
holoptic males, but ranges to box-like with a horizontal frons, long face and
long antennae. The frons of holoptic males is narrow and usually lacks nay lower
orbital bristles curving forward; almost always two pairs of such bristles occur
in females and dichoptic males. Frontal bristles usually bend inward. Ocelli
are rarely absent and the ocellar setae usually curve forward. The antennae
range from tiny to as long as head height; the second segment bears setae on
the front; the arista is normally bare, but sometimes is feather-like. The face
is usually concave or flat, but sometimes convex; there is normally a strong
vibrissa. In some species the labium is sometimes extremely long and slender.
The postpronotum usually has four strong bristles, but there can be as few as
two and as many as five. The scutum can be extensively bristled, especially
in the subfamily Goniinae to almost devoid of them (many species in the subfamily
Phasiinae); there are usually three presutural dorsocentral bristles and three
or four postsutural ones. The scutellum usually bears three or four pairs of
marginal bristles and one pair on the disc. The subscutellum is well-developed,
in side view usually evenly convex from top to bottom. The meron always has
a vertical row of bristles. The wings are normally transparent, but some are
marked or spotted and others are all dark. Vein M is bent forward, ending in
the wing margin just behind vein R4+5 or in vein R4+5 itself, thus closing cell r4+5. The abdomen is variably shaped, from
petiolate to broad, from convex above to flattened to globose. It is usually
more or less covered with strong, erect bristles, but these are lacking in some
As far as is known, all
the larvae of the Tachinidae are parasites of arthropods, and all except a few
of these arthropod hosts are insects. The family plays a major role in the control
of populations of other insect groups and many species have been used in the
biological control of insect pests. Some tachinids, mostly in the subfamilies
Phasiinae and Exoristinae stick a conspicuous, undeveloped egg directly on the
cuticle of the host. This is considered the most primitive system of attack
on an exposed host and modifications to speed up the penetration of the larvae
into the host have developed. The females of most Phasiinae have abdominal structures
for inserting eggs into the host’s body. The fast majority of species in the
Tachinidae, however, store the eggs in an ovisac (uterus) until embryonic development
is complete. Unlike sarcophagids, which deposit active larvae that have hatched
within the female, all tachinids lay eggs that hatch (but sometimes within seconds)
after deposition. Most hosts avoid direct attack during the day while female
flies are active; either the hosts are concealed in the soil, leaf litter or
other substrates or are protected by silken webs, such as those produced by
tent caterpillars. A female in the tribe Goniini lays thousands of minute eggs
where the host will eat them along with its food; the larvae burrow into the
host through the gut wall. However, most tachinids broadcast their eggs on damaged
foodplants or other places likely to support their host; the larvae lie in wait
for a suitable host to pass by, board it and burrow inside. Still others (tribe
Dexiini) have larvae that burrow into the substrate where they hatched and actively
search for the host in soil, rotten wood and other places. Most tachinids, including
most species in the subfamilies Tachininae and Exoristinae, attack the larvae
of Lepidoptera. The Phasiinae parasitize true bugs, especially the Pentatomidae,
Coreidae, Nabidae and Lygaidae. Beetle larvae of the families Scarabaeidae,
Cerambycidae and Elateridae are hosts for the Dexiini in the subfamily Dexiinae;
adult scarabs are attacked by species of Cryptomeigenia Brauer &
Bergenstamm and adult carabids by those of Zaira Robineau-Desvoidy. Certain
members of the tribe Blondeliini parasitze larval and adult chrysomelid beetles.
The Orthoptera are hosts for several genera. The tachinine genus Ormia Robineau-Desvoidy is nocturnal and homes in on the songs of long-horned grasshoppers
and crickets. Other genera attack stick insects, mantids, cockroaches and earwigs.
A few flies are hosts – Tipulidae are parasitized by species of Admontia Brauer & Bergenstamm and Siphona Meigen and some tabanids
are hosts to Billaea Robineau-Desvoidy. In the Hymenoptera, some leaf-feeding
sawflies are known hosts, as are the adults of a few ants and some colonial
wasps. There are a very few records of tachinids parasitizing centipedes, spiders
and scorpions. Adult tachinids are active and eagerly search for sources of
sugar; they are particularly attracted to honeydew. Some, in search of nectar,
often visit flowers, especially those of the Asteraceae, and others feed on
tree sap. Males of many species congregate on sunny hilltops and ridges to wait
for females. Species aggregate at specific sites in these places.
In the Diptera, the Family
Tachinidae is second only to the Tipulidae in the number of described species
-- at least 8000 species are known worldwide. There are published records of
about 303 tachinid genera containing 1345 described species in the Nearctic;
with 152 genera and 393 species known from BC. The family is mainly tropical
and southern parts of Canada have a more diverse fauna than regions farther
north. The related family Rhinophoridae contains tachinid-like flies that share
characters of primitive tachinids, calliphorids and sarcophagids; species parasitize
woodlice (terrestrial isopods). There are no native North American rhinophorids,
but two species, introduced from Europe like their crustacean hosts, live in
Canada. They have not been recorded in BC. Perhaps the most recognizable members
of the subfamily Phasiinae in BC are the three species of Gymnosoma Meigen,
rotund and almost bristleless flies that attack big, green Chlorochroa Stål stink bugs. Gymnosoma fuliginosum Robineau-Desvoidy is probably
the most widespread species in the province. The four species of BC Cylindromyia Meigen are also distinctive parasites of pentatomid bugs; C. intermedia (Meigen)
and C. fumipennis Bigot are the more common of these slender, red and
black species. The subfamily Dexiinae includes Uramya halisidotae (Townsend),
a black fly with grey bands on the abdomen; it has been reared from Lophocampa
argentata (Packard) (Silverspotted Tiger Moth) and Malacosoma californicum (Packard) (Western Tent Caterpillar). In the Exoristinae, the genus Gonia Meigen (14 BC species) specializes in the speciose moth family Noctuidae; G.
porca Williston is a widespread western species. Compsilura concinnata (Meigen) is considered the most polyphagous of all tachinids – it has over 200
different recorded hosts. It was introduced from Europe, mainly to control Gypsy
Moth (Lymantria dispar (Linnaeus)) in eastern North America, but has
spread west to the Pacific coast. It attacks many insects, from Pissodes Germar weevils to Cimbex Olivier sawflies, from Limenitis Schank butterflies to Smerinthus Latreille sphinx moths. There are eight
species of Winthemia Robineau-Desvoidy in the province; the western-ranging W. occidentis Reinhard helps control Lambdina fiscellaria (Guenee)
(Hemlock Looper). The Holarctic W. quadripustulata Fabricius parasitizes
over 50 known moth species, including some of the most damaging cutworm moths. Tachinomyia variata Curran is big, black and grey and bristly; it is
a major parasite the Western Tent Caterpillar. Cyzenis albicans (Fallén),
another goniine, was introduced to southwestern BC to control Winter Moth, Operophtera
brumata (Linnaeus), a pest of Garry Oak, fruit trees and many other plants.
The subfamily Tachininae mainly has Lepidoptera hosts. The most speciose genera
in BC are Panzeria Robineau-Desvoidy (18 species), Tachina Meigen (17 species) and Peleteria Robineau-Desvoidy (17 species).
Tachina algens Wiedemann is a particularly common BC representative of the genus Tachina;
it is black with yellow wingbases and dense yellow setulae behind the head.
Peleteria iterans (Walker) is grey with an orange abdomen marked with black along the midline. Adejeania vexatrix (Osten Sacken), a western species ranging from BC
to Mexico, is impressively big, orange and very bristly. Hystricia abrupta (Weidemann) could be described in the same way; it ranges all over North
America. Epalpus signifer (Walker), a noctuid moth hunter, is distributed
over much of North America; it is black with a prominent yellow patch at the
tip of the abdomen. The three species of Gymnocheta Robineau-Desvoidy in the province, all restricted to the West, are strikingly metallic green
or blue. The related Chrysotachina alcedo (Loew) also is metallic green. Siphona, with 11 species in the province, is a diverse group of small
tachinids that mainly parasitizes microlepidoptera. Siphona cristata Fallén,
however, attacks crane fly larvae.
Family HIPPOBOSCIDAE (Louse Flies and Keds) [Fig. 55]
Flies of the family Hippoboscidae
are flattened, rather tough and leathery looking flies, ranging from 1.5 to
12.0 mm long. They are usually setulose. The head is broad and somewhat flattened;
the mouthparts are thrust forward. The compound eyes are normally well developed
and horizontally elongate; ocelli are either present, vestigial or absent. The
inner vertical bristles are long, the outer ones are absent and the orbital
bristles are few to many. The lunule is usually bare, shiny and conspicuous.
The antennae are strongly modified and are more or less immovable; they lie
in deep pits. The first segment is usually present, but sometimes is fused to
the lunule and invisible; the rounded second segment is the largest and sometimes
bears a third, flattened, segment or a spatulate or branching arista. The one-segmented
palps form a sheath for the blood-sucking, retractible labium. The thorax is
flattened; the scutellum is usually large, often broadly rectangular. The wings
are usually fully developed, but in some genera that parasitize mammals, such
as Lipoptena Nitzsch and Neolipoptena Bequaert, the wings break
off after the fly settles on its host. In others, the wing is reduced to a small
flap or, as in Melophagus ovinus (Linnaeus), which lives in the fleece
of sheep, is a tiny knob. This species has lost its halteres, but they are normally
present in other species. The wing veins are usually crowded forward with the
posterior veins often fading towards the wing margin. Some species have greatly
reduced venation. The legs are strong, rather short and often well-bristled.
The coxae and femora are usually swollen; the apical tarsal segment is the largest.
The tarsal claws are large and strong, simple or forked; the empodium is setulose
or feathery and the pad-like pulvilli are often long and soft. The abdomen is
largely membranous with tergites and sterna mostly reduced.
Hippoboscids are ectoparasites
and feed on the blood of birds and mammals. The majority attack birds and are
often called louse flies; those on mammals (mostly ungulates) are frequently
called keds. The Sheep Ked (often erroneously called the sheep tick) is probably
the only species in North America that causes any economic losses; heavy infestations
of sheep sometimes result in anaemia and staining of the wool. This species
was introduced from Eurasia to sheep-producing temperate environments worldwide
and, apparently, no truly wild populations exist today. Those populations found
on bighorn and thinhorn sheep are thought to have transferred from domestic
sheep. Several species have been recorded biting humans, but this is a rare
and accidental phenomenon. Most species are not host specific, but rather seem
to inhabit a variety of hosts from a particular type of habitat.
Together, the Hippoboscidae,
Nycteribiidae and Streblidae are sometimes called the Pupipara, because they
appear to give birth to pupae. This is inaccurate, in that the fully grown larva
is extruded by the female and immediately pupates afterwards. One at a time,
an egg and then a larva develop in the female uterus, nourished by secretions
from the so-called milk glands. A female can produce seven or eight or more
mature larvae during her life.
The Family Hippoboscidae
is cosmopolitan, but is most diverse in the tropics and subtropics; about 200
species are named in 21 genera. In North America, 13 genera contain 31 described
species. At least 13 described species in 10 genera are known to occur in BC
based on published records and collections of BC Diptera. Most are in the subfamily
Ornithomyiinae and parasitize birds. Icosta ardeae (Macquart), a Holarctic
species, is common on various herons and bitterns and I. nigra (Perty) ranges from BC to Quebec and south to South America on hawks and falcons. Ornithoica vicina (Walker) is widespread in the New World and, on the
Pacific Coast, is collected mostly on wading birds. Two species of Ornithomyia Latreille are recorded in the province. O. fringillina Curtis,
widespread in the Northern Hemisphere, has been recorded on a wide range of
forest birds, including Blue and Spruce grouse, Cedar Waxwing, Varied Thrush
and Steller’s Jay. Ornithoctona erythrocephala (Leach) ranges across
Canada and into South America; it especially favours hawks and falcons. Olfersia
fumipennis (Sahlberg) is a Holarctic species widespread over much of North
America; it is collected regularly on Ospreys and Bald Eagles.
Species of the Subfamily
Lipopteninae normally parasitize even-hooved mammals, such as deer and sheep. Neolipotena ferrisi (Baequert), from western North America, is the only
member of its genus; it lives on deer in BC, mostly east of the Coast Mountains. Lipoptena has three Nearctic species, but only the western L. depressa (Say) occurs in the province; it is especially common on coastal
deer. The introduced Melophagus ovinus does not fly at all. It can be
a problem in BC sheep flocks and is also known from native wild sheep. Hippobosca
longipennis Fabricius (Subfamily Hippoboscinae), an Old World species that
attacks mammals of various types, including dogs, has been introduced to North
America on zoo animals. Evidently, it has yet to be recorded in BC.
Family NYCTERIBIIDAE (Nycteribiid Bat Flies) [Fig. 56]
Nycteribiid bat flies are
among the most specialized of all Diptera – they are wingless, dorsoventrally
flattened, spider-like flies, about 1.5 to 5 mm long. The small head, when at
rest, lies back on the mesonotum; during feeding it is rotated forward and downward.
It is mostly a dorsally sclerotized, helmet-like capsule; much of the front
and underside is membranous. The compound eye, which is sometimes absent, is
usually reduced to two ocellus-like facets. The antenna appears as a single
compound segment (evidently formed from the second and third segments), bearing
a branching arista. The piercing-sucking proboscis is short; the palps are usually
large and prominently bristled. The thorax is broad and flattened, mostly membranous
above and strongly sclerotized below. The scutellum is absent, but the postnotum
is usually rounded and raised. Unique to the Nycteribiidae, a movable crescentic
row of spines (thoracic ctenidium), is present in front of the middle coxa.
The wings are absent, but halteres are present, lying in a groove, which may
be covered by a flap arising from the inner edge of the groove. The legs are
rather long and stout, variously armed with setulae and bristles. The first
segment of the tarsus is usually longer than the others combined; the last segment
is usually the broadest. The claws are simple, but large and stout; the empodia
are absent. Normally, the abdomen has both the tergites and sterna bearing prominent
rows of bristles and setulae on the hind margins.
Nycteribiids are blood-feeding
ectoparasites of bats. Like species in the related Hippoboscidae and Streblidae,
those of the Nycteribiidae are viviparous, giving birth to fully developed larvae.
One mating produces multiple larvae; the sperm is stored in the two spermathecae
-- the ovaries ovulate alternately, and one egg at a time enters the uterus
after fertilization. The larva is nourished from special glands and development
takes about nine days. The female normally deposits the mature larva on the
vertical surface of the bat roost, pressing it into place; the larva pupates
immediately. Most species of nycterbiids are apparently bat species or genus
specific although there may be considerable variation in host-parasite relationships
over the range of a species of fly.
The family Nycteribiidae
ranges worldwide except for the polar regions and contains about 260 described
species in 13 genera. Basilia Ribeiro, the only genus known in North
America, contains over 40 species, but only five of these are recorded in North
America. Almost all species of Basilia parasitize bats of the Family
Vespertilionidae; all resident bat species in BC belong to this family. Basilia
forcipata Ferris is the only known Canadian species; it was collected in
BC on a Little Brown Myotis (Myotis lucifugus LeConte) in Midday Valley
near Merritt. However, an apparently undescribed species of Basilia was
collected in 1938 off a specimen of the Western Mastiff Bat (Eumops perotis (Schinz)) that showed up in Essondale, hundreds of kilometres north of its usual
range in southern California and Arizona.
Family STREBLIDAE (Streblid Bat Flies) [Fig. 57]
Streblid bat flies are small,
rather setose and bristly flies ranging from 0.75 to 5.0 mm long. They are either:
compressed from side to side and flea-like, dorsoventrally flattened, or have
a more typically dipteran convex body form. The head is normally small, often
compressed laterally or flattened, and bearing conspicuous bristles and setulae.
The compound eyes are reduced, the number of facets ranging from none to 36,
but usually 7 to11; ocelli are absent. The antennae are small, with the first
segment fused to the head, the second with a furrow above and mostly concealing
the oval third segement, which bears a comb-like arista. The mouthparts are
piercing and sucking. The thorax varies from convex and globose (e.g. BC species
in the Subfamily Trichobiinae) to slightly convex, laterally compressed or dorsally
flattened; the pronotum is scarcely visible. The scutellum is normally obvious,
its hind edge angulate in New World genera and bearing one to ten (usually four)
long bristles. The legs are variable in length and thickness, but the hindleg
is often much longer than the others. The tibiae lack apical spurs; the tarsal
claws are large and adapted for clinging. Most species have fully developed
wings, but some have shortened or narrowed wings and some lack them altogether.
The wing veins usually have setae above and below. When well developed (as in
most North American species), the veins run longitudinally; the costa ends at
the apex of R4+5; the subcosta is faint, fused with R or absent.
Vein Rs forks at about one-third the wing length, vein R2+3 ends just before the wing tip and vein R4+5 ends at the tip. Crossvein
r-m is usually at about the midlength of the wing and dm-cu , which joins the
unbranched vein M to vein CuA1, is near the wing tip.Veins CuA1 and CuA2 are fused for much of their lengths, with vein CuA2 branching off at about two-thirds the wing length and joining A1 near the wing margin. The abdomen is mostly membranous and sac-like, especially
in egg-bearing females. Tergites 1 and 2 are fused, with strong lateral lobes
bearing bristles and setulae.
Streblids are obligate,
blood-feeding ectoparasites of bats; both sexes feed often and usually die quickly
if deprived of blood. Females of one Old World genus, Ascodipteron Adensamer,
burrow in the host’s skin and become sac-like endoparasites. Species of Trichobius Gervais sometimes bite humans. The larvae develop singly in the female’s abdomen,
where they feed on special glandular secretions. When fully grown, the larva
is extruded and immediately pupates; large numbers of puparia often encrust
the floors or walls of the bat roosts. Adults must feed before mating and, apparently,
mating is required each time a new egg is produced. Streblids frequently parasitize
colonial, cave-dwelling bats, but most New World species occur on forest-roosting
bats. Solitary bats are seldom attacked. Flightless streblids mostly inhabit
bats that eat fish or fruit. The adultsof most fully winged NewWorld species,
although highly mobile, stay close to their hosts; most are host specific or
live on a few species of closely related bats.
The Family Streblidae ranges
subtropically and tropically on all the main continents and oceanic islands,
mostly between 40 degrees north and south. It contains about 220 species in
32 genera. There are six described species in three genera in the Nearctic.
One species, Trichobius corynorhini Cockerell, lives as far north as
BC in the West and West Virginia in the East. This is the only known streblid
species in Canada; it overwinters on bats hibernating in caves.
Families of DIPTERA in British Columbia
extending at least to midpoint of abdomen, and of normal shape.
Wings absent or greatly
with 4 or more flagellomeres which are usually uniform in shape and size,
apical segments not modified into a stylus or arista. Palpus usually with
3-5 segments, rarely with one or two segments.
usually more compact than Nematocera, very rarely more than 8 segments,
apical segments often modified into a stylus or arista those with 4 or
more flagellomeres have non-uniform sized and shaped segments. Palpus
never with more than 2 segments.
Ptilinal suture and
Ptilinal suture and
BRACHYCERA and MUSCOMORPHA, ASCHIZA (Key III)
Thorax usually strongly
flattened, hind coxa widely separated, tarsal claws large, strongly recurved,
often toothed. Adults ectoparasitic on mammals or birds.
HIPPOBOSCOIDEA (Key IV)
Thorax not overly
flattened, hind coxa close together, tarsal claws small, somewhat curved,
never toothed. With very few exceptions (some members of the family Carnidae)
adults not ectoparasitic on mammals or birds.
Greater ampulla present
as a distinct bulbous swelling below wing base and fused to the anepimeron.
Vibrissae usually present. Antennal pedicel always with an entire dorsal
OESTROIDEA and MUSCOIDEA (Key V)
Greater ampulla usually
absent, but if present (some Tephritidae, Psilidae and Periscelididae)
then the vibrissae are absent (some Milichiidae with vibrissae have a
bulbous swelling – the lesser ampulla, near the wing base and the anepimeron
however in these cases there is a distinct white, membranous area between
the anepimeron and the lesser ampulla). Antennal pedicel usually with
dorsal seam incomplete or absent.
ACALYPTRATAE (Key VI)
Key to Families of NEMATOCERA
Wing with a network
of delicate crease-like lines between the main veins, and with the number
of main veins fully or partially reduced; anal lobe strongly projected
towards the base of the wing.
Wing lacking a network
of delicate crease-like lines between the main veins, number of main veins
sometimes reduced; anal region of wing usually not as strongly projecting
towards base of wing as above.
with 11-13 flagellomeres, apical flagellomere approximately equal in length
to preceding segments; wing relatively long and narrow.
with 4 flagellomeres, apical segment greatly elongated in males; wing
broad and fan-like.
Halter with a basal
Halter lacking a basal
Wing with veins A1 and A2 reaching wing margin as distinct veins.
Wing with at least
vein A2 absent or fading out before reaching wing margin.
Vein A2 usually more than ½ length of vein A1 and fairly straight.
Ocelli absent or greatly reduced.
Vein A2 usually much less than ½ length of vein A1 and strongly curved
at apex. Ocelli present, distinct.
Radial vein with 5
separate branches reaching the wing margin; discal cell present; anal
lobe usually well developed.
Radial vein usually
with fewer than 5 branches reaching the wing margin; if 5 separate branches
reaching the margin, then discal cell absent and anal lobe poorly developed.
Costa continuing around
the wing onto the hind margin (often weaker beyond wing tip), well beyond
the last radial vein.
Costa ending near
last branch of radial vein, near wing tip; if costal character indistinct
(Pachyneuridae) then radial vein with 3 branches and a crossvein, r-r,
which forms a closed cell between R2+3 and R4+5.
First tarsomere much
shorter than second and both more or less fused giving the appearance
of 4 tarsal segments.
Cecidomyiidae (in part)
First tarsomere longer
than the second, with distinctly 5 tarsal segments.
Ocelli always absent;
costa without a break beyond the insertion of R4+5.
Ocelli usually present,
if absent the costa has a break just beyond the insertion of R4+5.
Cecidomyiidae (in part)
Wing with 6 or 7 veins
reaching margin; antennae about as long as head, flagellum short and slender
with 2 or 3 bristles at apex.
Wing with 9 to 11
veins reaching margin; antennae at least twice length of head, flagellum
not reduced and usually with rings of setae on all flagellomeres.
Medial vein with 3
branches; subcosta incomplete or ending in costa or R1 before
middle of wing; very setose, moth-like flies.
Medial vein with 2
branches; subcosta complete, ending at costa at or beyond midpoint of
wing; flies at most moderately setose, mosquito-like.
Flattened scales present
on wing veins., head legs, and often other parts of body. Proboscis long,
extending well beyond clypeus.
Scales absent from
wing veins, head, legs, and other body parts although narrow setae often
present. Proboscis short, at most extending to just beyond clypeus.
Wing veins with dense
covering of long narrow setae; base of vein R2+3 straight.
Antennal flagellomeres with long setae in distinct rings.
Wing veins with sparse
covering of very short; base of vein R2+3 strongly curved forward,
antennal flagellomeres with short sparse indistinctly arranged setae.
Antennae short, about
as long as head); flagellum with short setae in both sexes. Wing relatively
broad with weakened posterior veins.
Antennae long, much
longer that head; flagellum with distinct long setae especially in males.
Wing relatively narrow, with posterior veins usually prominent.
Medial vein almost
always forked, with M2 sometimes weakened at base, rarely faint
over entire length; never more than 2 branches of the radial vein reaching
the wing margin. Postnotum usually without a longitudinal groove. Females’
mouthparts usually with blade-like mandibles.
Medial vein never
forked, always lacking M2; usually with 3 branches of radial
vein reaching the wing margin. Postnotum usually with a longitudinal groove.
Neither sex’s mouthparts with functional mandibles.
Wing with radial vein
3 branched and with crossvein r-r forming a closed cell between R2+3 and R4+5.
Wing with radial vein
sometimes having 3 branches, but never with crossvein r-r forming a closed
cell between R2+3 and R4+5.
Wing with discal cell
present, medial vein with 3 branches.
Wing lacking a discal
cell, medial vein with never more than 2 branches.
Radius with 4 branches;
R2 and R3 appearing as 2 separate veins, with R2 short forming an oblique angle with R3 and joining R1 at costa; pair of shiny oval spots near middle of scutum.
Radius with 3 or fewer
branches; R2 and R3 never appearing as 2 separate
Wing with 2 closed
basal cells – br and bm, that are separate and closed on their distal
ends). Pulvilli and empodium well and equally developed; acropod with
3 similar pads.
Wing almost always
(few exceptions in the family Mycetophilidae) with only one closed basal
cell -- either cells br and bm fused or with cell bm open distally.
Pulvilli at most weakly developed; acropod never with 3 similar pads.
Compound eyes nearly
meeting below the antennae, and holoptic above.
Compound eyes widely
separated below antennae with or without a narrow eye bridge above the
Tibiae without apical
spurs. Wing with costa ending well before apex of wing and usually with
only costa and radial veins darkly pigmented.
Tibiae with apical
spurs. Wing with costa ending at or near the apex of the wing and usually
with all veins darkly pigmented.
Compound eyes meeting
narrowly above antennae. Wing with base and forked portion of M subequal
in length and with fork bell-shaped
Compound eyes never
meeting above antennae. Wing usually with fork of M much longer than base
and lanceolate in shape
Key to Families of ORTHORRHAPHOUS BRACHYCERA
and MUSCOMORPHA, ASCHIZA
Key IV: Key to
Families of HIPPOBOSCOIDEA
each acropod with 3 similar shaped flattened pads below tarsal claws.
Vein CuA2 free or forming an acute angle with vein A1 near the wing margin.
Empodia usually setiform
or absent; if acropod with 3 pads them empodium much narrower and more
tapered than pulvilli; if empodia somewhat pulvilliform then CuA2 joining A1 at an obtuse angle far from the wing margin.
Head unusually small,
rarely exceeding ½ width of thorax; compound eyes of both sexes nearly,
to entirely, holoptic. Lower calypter extremely large, wider than head.
Head more than ½ width
of thorax; compound eyes never holoptic in females. Lower calypter smaller,
not as wide as head.
Branches of radius
and medial veins converging towards wing apex; branches of medial vein
curved forward and ending near apex of wing, and with a diagonal vein
running from distal end of cell br to posterior margin of wing.
Branches of radius
and medial vein diverging to wing apex; branches of medial vein meeting
wing margin behind apex and lacking a diagonal vein.
Costa ending near
Costa continuing beyond
wing apex, usually weaker along posterior margin of wing.
Costa usually ending
well before, rarely nearly at, wing apex; branches of R more or less crowded
anteriorly, and all ending in margin well before wing apex; cell d short,
usually little longer than wide. Tibial spurs usually absent.
Costa extending to
wing apex or slightly beyond; branches of R not crowded anteriorly, with
R5 ending at or beyond wing apex; cell d at least two times
as long as broad. Tibial spurs present on at least middle and hind tibiae.
Fore tibia with a
ventral apical spur.
Fore tibia without
a ventral apical spur.
Scutellum always setulose
and with 4 prominent spines on margin.
setulose, but never with 4 prominent spines
developed; posterior thoracic spiracle with a scale-like elevation immediately
or poorly developed.
with a slender non-annulated arista. Wing with cell r1 closed
by vein R2+3 meeting costa at end of R1.
with a coarse annulated stylus.
Both upper and lower
calypteres large, subequal in size. First abdominal tergite deeply notched
in the middle of the posterior margin, and with a median suture.
Upper calypter moderately
large, lower one scarcely developed. First abdominal tergite without a
median notch or suture.
Proscutellum (a small
swelling between the scutellum and the mesonotum) present; aedeagal tines
of male terminalia absent; female with a well developed postabdomen, clearly
separated from the preabdomen.
aedeagal tines of male terminalia present; female with postabdomen not
clearly separated from preabdomen.
Clypeus exposed and
strongly convex, in profile with anterior surface bulging beyond parafacial,
and usually reaching dorsally to bases of antennae. Flagellum usually
with not more than 7 flagellomeres, and with distal ones frequently forming
a slender stylus or arista.
Clypeus recessed in
a deep facial groove and more or less flattened, in profile with anterior
surface depressed below level of parafacial, and not reaching dorsally
to bases of antennae. Flagellum usually with at least eight gradually
smaller flagellomeres, and with apical ones not forming a slender stylus
or arista except in the genus Dialysis.
wing margin near A1 or joining A1 near wing margin;
if joining A1, then CuA2 at least 1.5 times longer
than apical section of A1, except in a few Bombyliidae.
or vestigial, or joining A1 far from wing margin; if joining
A1, then CuA2 at most scarcely longer than apical
section of A1, except in a few Empididae and a few Platypezidae.
Branches of M peculiarly
curved forward, more or less parallel to posterior wing margin at least
M1 ending freely in wing margin before wing apex.
Branches of M not
curved as above, but if somewhat bent forward then not ending freely in
long with a slender stalk-like base and strongly clubbed apex; stalk at
least twice as long as combined length of scape and pedicel. Only one
than head, without a stalk-like base; entire flagellum not much longer
than combined length of scape and pedicel. Three ocelli present.
Spurious vein evident
as a strong vein-like fold between Rs and M; M1 curved forward
roughly in line with crossvein dm-cu and joining unbranched R4+5 in a crossvein-like manner.
Spurious vein undeveloped;
M1 usually not curved forward in a crossvein-like manner, but
if curved forward then joining a furcated R4+5.
Head strongly hemispherical,
with compound eyes abnormally large and almost meeting both above and
below antennae. Flagellum with a dorsal arista. R4+5 is unbranched;
costa ends at wing apex.
Head usually not hemispherical,
but if so then flagellum without a dorsal arista. R4+5 usually
furcated: costa usually continuing around wing.
Vertex usually distinctly
excavated between eyes; ocellar tubercle below dorsal level of compound
eyes; compound eyes never holoptic. Face relatively long, with a cluster
or row of long bristles, the mystax. Proboscis stout, polished; labella
reduced and inconspicuous; hypopharynx protrusible, strongly developed
Vertex not or only
slightly concave; ocellar tubercle usually elevated above the dorsal level
of the compound eyes; compound eyes usually holoptic in males. Face relatively
short, sometimes setulose, but without a mystax. Proboscis short and stout
to long and thin, usually dull pruinose; labella usually well-developed
and conspicuous; hypopharynx not protrusible, not developed for piercing.
Wing with cell bm
truncate distally and with four corners from which arise four separate
veins (M1+2, M3, CuA1, CuA2)
base of cell m3 truncate.
Wing with cell bm,
when present, pointed distally and with three corners from which arise
three separate veins (M1+2, M3+CuA1 and
CuA2); base of cell m3, when present, pointed.
Wing with cell dm
absent, and with R4+5 and M1+2 rather similarly
forked, each fork not longer than its base.
Wing with cell dm
usually present, but if not the R4+5 and M1+2 not
with a minute stylus concealed in a subapical pit. Crossvein r-m at or
beyond middle of wing; M unbranched and curved forwards, joining R4+5 or closely approaching it in the wing margin.
with an elongate, fully exposed stylus or arista. Crossvein r-m well before
middle of wing or absent; M branched or unbranched, sometimes curved forward,
but not as above.
Wing pointed at apex
with peculiar linear venation; main veins except subcosta and R3 with black setulae above. Antennal flagellum rounded, with a terminal
arista. Slender brownish or yellowish flies, 2-5 mm long.
Wing rounded at apex,
and with radiating venation; veins at least in posterior half of wing
not setose. Antennal flagellum, body size, and colour variable.
Wing with branches
of R strongly thickened and crowded into anterior base, and with four
other weak and peculiarly aligned veins in remainder of wing blade; costa
ending near middle of anterior margin.
Wing with branches
of R not strongly thickened and crowded anterobasally, and with other
veins normal; costa extending at least to wing apex.
Antenna with pedicel
much longer than flagellum; flagellum with a dorsal three-segmented arista.
Mid coxal prong strongly developed.
(exception lacking a ptilinal suture) Sciomyzidae:
Antenna with pedicel
not or scarcely as long as flagellum; if arista three-segmented, then
terminally situated. Mid coxal prong absent.
Wing with both A1 and subcosta reaching wing margin, and with cell cup acute at posterior
apex. Hind tarsus, at least in male, with one or more basal tarsomeres
expanded and flattened. Arista three-segmented, terminally situated.
Wing rarely with A1 reaching wing margin, but if so either subcosta incomplete or cell cup obtuse or rounded at posterior apex. Hind tarsus not modified as above.
Arista or stylus two-segmented, terminally or dorsally situated.
at or near level of crossvein h, distal to crossvein h by, at most, length
of crossvein h; crossvein r-m in basal fourth of wing; cells bm and dm
confluent, that is, crossvein bm-cu absent; subcosta usually abruptly
curved posteriorly and fused with R1, except in the subfamily
well distal to level of crossvein h, usually distal to it by more than
length of crossvein h; crossvein r-m distal to basal fourth of wing; cell
bm usually separated from cell dm (when cell dm is present) by crossvein
bm-cu; subcosta usually joining costa or ending freely, never abruptly
Compound eyes large,
horizontally oval, at least ¾ as high as head, with at least 100 very
small facets. Posterior wing veins weaker than anterior veins. Ectoparasitic
on birds and mammals except bats.
Compound eyes, if
present, small, round, never more that ½ as high as head, and with less
than 40 relatively large bead-like facets. Wing veins relatively uniform
in strength. Ectoparasitic on bats.
Key V: Key to
Families of OESTROIDEA and MUSCOIDEA
Large (9-25 mm long)
heavy-bodied, finely setulose flies which lack large setae and resembling
honeybees, bumblebees or carpenter bees. Head bulbous with greatly reduced
or atrophied mouthparts, no vibrissae, and small recessed antennae. Meron
usually with a cluster of long setae. All larvae obligate parasites of
Usually smaller (1-15mm
long) normally setose flies. Head usually with well-developed mouthparts,
vibrissae, and normal-sized antennae. Meron bare or with a row of bristles,
sometimes with additional scattered fine setulae. Larvae rarely parasites
Meron with a row of
bristles, sometimes with additional scattered fine setulae.
or weakly developed.
Abdomen and usually
thorax with a distinct metallic blue or green sheen. Palpus usually orange-yellow.
Calliphoridae (in part)
Abdomen usually mostly
dull, variegated gray, brown or black, sometimes shiny black, but never
metallic blue or green. Palpus blackish to yellowish.
Thorax with silky
wavy yellowish setulae as well as normal black bristles and setulae.
Calliphoridae (in part)
Thorax without silky
Scutum usually with
three conspicuous black stripes on a gray background. Notopleuron usually
with 3 or 4 bristles. Hind coxa usually with setulae on posterior surface.
Arista usually plumose.
Scutum with or without
black stripes. Notopleuron always with only 2 bristles. Hind coxa always
without setulae on posterior surface. Arista plumose to bare.
Calliphoridae (in part)
forward beyond tip of A1, with course of A1 (if
extended) intersecting A2 before wing margin; subcosta always
nearly straight on apical 2/3. Hind tibia always with a strong bristle
near middle of dorsal surface as well as a preapical dorsal bristle.
curved forward beyond tip of A1, with course of A1 not intersecting A2 before wing margin; subcosta usually distinctly
curved forward on apical half or less. Hind tibia rarely with a strong
bristle near middle of dorsal surface as well as a preapical dorsal bristle
(sometimes a similar bristle- the calcar, present on posterodorsal surface).
Palpus absent. Crossveins
r-m and dm-cu separated by a distance not or scarcely greater than length
of crossvein dm-cu; crossvein bm-cu partially atrophied.
Anthomyiidae (in part)
Palpus present. Crossveins
r-m and dm-cu usually more widely separated; crossvein bm-cu usually complete.
reaching wing margin even as a fold; lower calypter broad, never linear.
Muscidae (in part)
reaching wing margin at least as a fold. if not then lower calypter linear.
with fine pale setae on apicoventral surface; frons usually narrower in
male than in female; if scutellum bare on apicoventral surface and frons
wide in male then frons with strong interfrontal bristles. Occiput never
with fine pale setulae, only with black bristles and setulae. Katepisternum
usually with 2 to 4 bristles; lower calypter linear to broad.
Anthomyiidae (in part)
Scutellum bare on
ventral surface; frons wide in both sexes and lacking interfrontal bristles.
Occiput usually with numerous fine pale setulae, sometimes between black
bristles and setulae. Katepisternum usually with 1 bristle. Lower calypter
Key to Families of ACALYPTRATAE in British Columbia
very long and slender, frequently 2 or more times longer than head; pedicel
usually longer than first flagellomere. Crossvein sc-r present or cell
cup distinctly longer than cell bm, or with both characters present
simultaneously; M joining R4+5 or closely approaching it.
shorter and stouter, not longer than head except in some Milichiidae and
Chloropidae where it is elbowed; pedicel usually shorter than first flagellomere,
but if longer then crossvein sc-r absent and cell cup shorter than
cell bm; M approaching R4+5 or not.
Ocelli and mid coxal
prong absent; medium to large flies with heavily marked wings.
Ocelli usually present;
if absent, mid coxal prong present; size variable, wings marked or unmarked.
Hind tarsus with first
tarsomere distinctly swollen and usually shorter than second tarsomere.
Subcosta always incomplete; CuA1 usually incomplete.
Hind tarsus with first
tarsomere not swollen and longer than second tarsomere. Subcosta complete
or incomplete; CuA1 usually complete.
bent forward at almost 900, weakened beyond the bend and ending
at subcostal break; wing almost always with markings. Pedicel with a dorsal
cleft. Vibrissae absent. Greater ampulla usually weakly distinguishable
and anepimeron always with bristles or setulae or both.
Subcosta less abruptly
bent. Not agreeing with one or more of the remaining characters.
Slender bodied flies
with long slender legs. R4+5 and M meeting
or strongly converging at wing margin; subcosta always complete.
Usually stouter flies
with shorter heavier legs. R4+5 and M usually subparallel or
divergent at wing margin; subcosta complete or incomplete.
Eyes very large, distinctly
higher than long, and closer together in male than female. Ocellar bristles
present. R1 setose above. Katepisternum evenly pilose, but
without large bristles.
Eyes smaller than
above, not much higher than long, and equidistant in both sexes. Ocellar
bristles absent. R1 not setose. Katepisternum never evenly
pilose, always with one or more large bristles.
or nearly so, ending at costa or just short of it and free from R1 distally.
not reaching costa, often fusing with R1 distally.
Costa without a subcostal
Costa with a subcostal
spiracle with one or more fine bristles on lower margin. Form usually
ant-like; head subspherical; palpus usually vestigial; abdomen usually
elongate and basally constricted.
spiracle without bristles or outstanding setulae. Form usually not ant-like;
palpus usually well-developed.
below posterior thoracic spiracle; thorax distinctly flattened. Squatty
and strongly bristled flies.
thorax not very flattened. Form and bristling variable.
Face broadly membranous
and sunken in middle; vibrissa present.
Face uniformly sclerotized
and convex in middle; vibrissa absent.
frons with a pair of cruciate interfrontal bristles. Costa without humeral
break. All tibiae with a preapical dorsal bristle.
Clusiidae (in part)
Frons without cruciate interfrontal bristles. Costa with humeral break.
All tibiae without a preapical dorsal bristle.
Some or all tibiae
with a preapical dorsal bristle.
All tibiae without
a preapical dorsal bristle.
almost parallel, divergent, or absent.
Clypeus large and
prominent, in profile distinctly bulging beyond lower margin of face.
Pedicel always short.
Clypeus small and
withdrawn, in profile more or less concealed under lower margin of face.
Pedicel usually elongate.
convergent or absent. Clypeus small and withdrawn. Female with a flexible
divergent or absent. Clypeus large and prominent. Female with rigid shaft-like
distinctly developed, divergent. Katepisternal bristle present.
Otitidae (in part)
absent or very weakly developed. Katepisternal bristles absent, though
setulae or pile commonly present.
but sometimes weak in the family Tethinidae.
but subvibrissal bristles sometimes vibrissae-like.
Costa with a distinct
humeral break as well as a subcostal break.
Costa without a humeral
humeral break, with a subcostal break only.
Gena broad, with a
row of bristles in the middle. Proboscis with a stout bulbous prementum
and short inconspicuous labella.
Carnidae (in part)
Gena usually narrow,
but if broad then bristles confined to lower margin. Proboscis with slender
prementum and long conspicuous labels folded back along prementum.
Milichiidae (in part)
Pedicel with an angular
though sometimes weak projection on outer side. Arista subapical. Frons
with 2 to 5 strong more or less equally spaced mostly reclinate fronto-orbital
bristles, with at most only the lowest one inclinate.
Clusiidae (in part)
Pedicel without an
angular projection. Arista dorsobasal. Frons usually with fewer more or
less equally spaced fronto-orbital bristles, but if with 2-5 (Agromyzidae
and some Otitidae), then 2-3 of the lower ones are strongly inclinate.
convergent or absent.
Frons always with
3-5 strong inclinate frontal bristles that are relatively similar to the
two reclinate orbital bristles in size and spacing.
Agromyzidae (in part)
Frons seldom with
any strong inclinate frontal bristles, but if one or two present then
these positioned distant from and inclined oppositely to the two lateroclinate
All tibiae without
a preapical dorsal bristle. Costa not spinose; A1 fading out
on apical third or more, never traceable to wing margin. Vibrissae and
postocellar bristles weakly differentiated to virtually absent.
Tethinidae (in part)
All tibiae with a
preapical dorsal bristle. Costa spinose, except in some Heleomyzidae in
which A1 is traceable to wing margin. Vibrissae and postocellar
Ocellar bristles arising
on ocellar triangle above anterior ocellus.
Ocellar bristles arising
just outside ocellar triangle beside or slightly below anterior ocellus.
Halter black. Anepisternum
with a row of strong bristles posteriorly. Frons, face, thorax, abdomen,
and legs (excluding tarsi) black, usually with metallic reflections. Stout
bristly flies with broad flat abdomen; female with lance-like ovipositor.
Halter usually whitish,
but if halter blackish, then anepisternum without a row of strong bristles,
and/or head, thorax, abdomen, and legs not as extensively black. Form
Chyromyidae (in part)
divergent or absent.
Scutum with one or
more presutural dorsocentral bristles. Cell cup without an angular
extension at posterior apex. Disc of proepisternum always bare.
Scutum usually without
presutural dorsocentral bristles, but if present then cell cup with an angular extension at posterior apex or disc of proepisternum setose,
Otitidae (in part)
Costa without subcostal
or humeral break.
Costa with at least
a subcostal break present.
A1 strong; cell cup complete. Arista bare or micropubescent.
A1 atrophied; cell cup incomplete or absent. Arista
bare to plumose.
costa in basal third of wing; R4+5 and M distinctly convergent
distally. Postocellar setae weak or absent.
costa near middle of wing; R4+5 and M not convergent. Postocellar
A1 absent or vestigial, never forming a closed cell cup;
crossvein bm-cu absent, making cells bm and dm confluent.
A1 present, always forming a closed cell cup; crossvein
bm-cu usually present, making cells bm and dm usually separate.
Costa with a subcostal
break only, without a humeral break; CuA1 usually with a kink
marking the position of atrophied crossvein bm-cu. Arista bare or micropubescent,
Costa with both a
subcostal and a humeral break; CuA1 without a kink. Arista
bare to long plumose.
Face strongly convex;
subcranial cavity usually very large. Postocellar bristles absent; pseudopostocellar
bristles, if present, divergent.
Face concave; subcranial
cavity normal. Postocellar bristles present, convergent or subparallel.
Carnidae (in part)
an outstanding bristle, though frequently setulose (Figs. 4.106-107).
Vibrissae absent and gena without a vibrissa-like bristle.
has one or more enlarged bristles. Vibrissae present or absent; gena with
or without a vibrissa-like bristle.
with two bristles; anepisternum with an enlarged bristle, in addition
to fine setulae. Ocelli situated far forward, with the anterior one about
midway between the vertex and antennae.
Notopleuron with one
bristle, the posterior one; anepisternum without a bristle, with fine
setulae only. Ocelli situated near vertex, with the anterior one on dorsal
third of frons.
Costa with both a
humeral and a subcostal break.
Costa without a humeral
break, with a subcostal break only.
Long axis of antenna
strongly elbowed, with flagellum distinctly decumbent; arista frequently
Long axis of antenna
nearly straight, with flagellum more or less porrect. Arista bare or shortly
Costa with small evenly
spaced erect spinules beyond subcostal break. Proclinate orbital bristle
arising dorsolaterally to lowermost reclinate orbital bristle.
Costa without erect
spinules, with ordinary reclinate setulae only. Proclinate orbital bristle
usually arising ventromedially to reclinate orbital bristle; if arising
above reclinate orbital bristle then dorsomedially to it.
Gena broad, with a
row of bristles in middle. Proboscis with stout bulbous prementum and
short inconspicuous labella.
Carnidae (in part)
Gena usually narrow,
but if broad, then bristles confined to lower margin. Proboscis with slender
prementum and long conspicuous labella folded back along prementum.
Milichiidae (in part)
All tibiae with a
preapical dorsal bristle. Frons with two reclinate orbital bristles above
and one inclinate frontal bristle below.
All tibiae without
a preapical dorsal bristle. Fronto-orbital bristles not as above.
Frons with a single orbital bristle.
bare, but if setulose, then frons with more than one orbital bristle.
always present and divergent.
Agromyzidae (in part)
convergent or absent (there are a pair of pseudopostocellar setulae are
present in some Tethinidae and are easy to confuse with true postocellars
which are absent in all Tethinidae).
Fore femur usually with a strongly developed ctenidial spine.
Fore femur usually without a distinct ctenidial spine.
proepimeral bristles present.
Tethinidae (in part)
always absent; proepimeral bristle absent; except in some Aphaniosoma.
Chyromyidae (in part)
Key to Families of Wingless Diptera in British Columbia
with two or more distinctly separate flagellomeres, exclusive of stylus
Flagellum with a single
consolidated segment, exclusive of stylus or arista.
At least one ocellus
Mesoscutum with a
complete V-shaped suture.
Tipulidae (in part)
a complete V-shaped suture.
Compound eye minute,
reduced to one facet.
Cecidomyiidae (in part)
Compound eye large,
Tipulidae (in part)
Tibiae without apical
Cecidomyiidae (in part)
Tibiae with apical
spurs, although sometimes very short.
Eye bridge present.
Sciaridae (in part)
Eye bridge absent.
Body about 2 mm long.
Sciaridae (in part)
Palpus with three
or more segments. Body at least 4 mm long.
Antennal pedicel swollen;
flagellum at least twice as long as broad and with a minute apical setae.
Remnant of larval eye strongly apparent. Abdomen about three times as
long as remainder of body.
Antennal pedicel not
swollen; flagellum less than twice as long as broad and usually with an
elongate stylus or arista. Remnant of larval eye not apparent. Abdomen
less than twice as long as remainder of body.
Middle and hind coxae
widely separated ventromedially; tarsal claws strongly recurved and toothed.
Ectoparasites of bats, birds or mammals.
Coxae not widely separated
ventromedially; tarsal claws simple. Usually not ectoparasites of bats
or mammals, sometimes associated with nesting birds.
Head vertically oriented,
folded back into groove on mesoscutum. First tarsomere of each tarsus
very elongate, at least as long as remainder of tarsus. Ectoparasites
oriented, not folded back. First tarsomere of each tarsus short, subequal
to second tarsomere. Parasites of bats, birds or mammals.
Compound eyes always
present, large, horizontally oval, at least ¾ as high as head, with at
least 100 very small facets. Ectoparasitic on birds and mammals except
Compound eyes sometimes
absent, if present, small, round, never more than ½ as high as head, and
with less than 40 relatively large bead-like facets. Ectoparasitic on
Arista with 3 aristomeres.
Arista with 2 aristomeres.
Proboscis short and
retracted. Vertex excavated. Compound eye pubescent.
and projecting. Vertex convex. Compound eye bare.
First tarsomere of
hindleg swollen, shorter than second tarsomere.
First tarsomere of
hindleg not swollen, longer than second tarsomere.
Propleuron with a
a vertical ridge.
Face strongly convex;
subcranial cavity unusually large.
Face concave; subcranial
absent; frons with a single reclinate orbital bristle. Reduced wing with
an apical spot.
present; frons with at least two orbital bristles. Reduced wing, if present,
without an apical spot.
subparallel; gena with a row of strong bristles in middle. Associated
with nesting birds.
convergent; gena without a row of strong bristles in middle. Not associated
with nesting birds.
All tibiae without
a preapical dorsal bristle; fore femur with a strong ctenidial bristles.
Frons with two strong reclinate fronto-orbital bristles on lower half.
Some or all tibiae
with a preapical dorsal bristle; fore femur without a ctenidial bristle.
Frons without strong fronto-orbital bristles on lower half.
Frons with a proclinate
orbital bristle. Arista plumose.
Frons without a proclinate
fronto-orbital bristle. Arista bare or micropubscent.