THE SPIDER WASPS (Pompilidae)
OF bRITISH cOLUMBIA

(photo)

by Scott Russell
Spencer Entomological Collection
Beaty Biodiversity Museum, University of British Columbia

View the BC checklist

The family Pompilidae (spider wasps) is a cosmopolitan group of some 5000 species of wasps which prey almost exclusively on spiders, giving rise to their common name - the spider wasps. While morphologically monotonous (Evans 1951b), these species range in size from a few millimetres long to among the largest of all hymenopterans; genus Pepsis, the tarantula hawks may reach up to 64 mm long in some tropical species (Vardy 2000). B.C.'s largest pompilid, Calopompilus pyrrhomelas, reaches a more modest body length of 19 mm among specimens held in our collection.

In North America, pompilids are known primarily from hot, arid areas, although some species are known from the Yukon Territories and at least one species can overwinter above the snowline in the Colorado mountains (Evans 1997). In most species, the females hunt, attack, and paralyse spiders before laying one egg on (or more rarely, inside) the spider. Prey preferences in Pompilidae are generally based on size, but some groups are known to specialize, such as genus Ageniella on jumping spiders (Araneae: Salticidae) and Tachypompilus on wolf spiders (Araneae: Lycosidae) (Evans 1953). The paralysed host is then deposited in a burrow, which may have been appropriated from the spider, but is typically prepared before hunting from existing structures such as natural crevices, beetle tunnels, or cells belonging to
other solitary wasps.

While most pompilids follow this general pattern of behaviour, in the Nearctic region wasps of the genus Evagetes and the subfamily Ceropalinae exhibit cleptoparasitism (Evans 1953). In these groups the female uncovers the buried spider of another pompilid and deposits her own egg in the book lungs of the spider. This egg will inevitably hatch before that of the first wasp, following which the larvae will consume the first egg and then the host spider. In some cases the female may consume the previous wasp's egg prior to laying her own (Evans 1953). Male pompilids and many females also feed on nectar.

The subfamilial taxonomy of this family follows that of Shimizu (1993) and the subsequent revision by Pitts et al. (2006). The classification and identification of the subfamilies Pepsinae and Ceropalinae follows that of Townes (1957) but note that genus Chirodamus is now Calopompilus and classified in the subfamily Pompilinae (Shimizu 1993). The taxonomy and species-level identification for subfamily Pompilinae is provided by Evans (1950, 1951a, 1951b) and Bradley (1944); however, the genus Pompilus has been revised by Day (1981) to be restricted to Old World species, elevating the North American subgenera Ammosphex, Arachnospila, and Anoplochares (among others not listed here) to genera. Wahis (1986) subsequently subsumed Ammosphex and Anoplochares into Arachnospila.

Keys provided by the Pompilid Project, which are modified from earlier keys of Evans and Townes, were also used in genus-level identification for subfamilies Pepsinae and Ceropalinae. Synonyms for North American species are provided by
Evans (1966) and Nomina Insecta Nearctica (1996). Information on the distributions of species was gathered primarily from the summaries provided by Evans (1950, 1951a, 1951b) and Townes (1957) as well as the catalogues of Krombein et al (1977). A useful supplement to the aforementioned keys is the excellent and freely-available Hymenoptera of the World (Goulet and Huber, 1993), which provides
clear, informative anatomical diagrams and will be particularly useful to workers who are unfamiliar with hymenopteran morphology.

Sixty-five (65) species of Pompilidae are known from British Columbia.

View the BC checklist.

Literature Cited

Bradley, J.C. 1944. A preliminary revision of the Pompilinae (exclusive of the Tribe Pompilini) of the Americas (Hymenoptera: Pompilidae). Transactions of the American Entomological Society 70: 23 – 157.

Day, M.C. 1981. A revision of Pompilus Fabricius (Hymenoptera: Pompilidae), with further nomenclatural and biological considerations. Bulletin of the British Museum (Natural History), Entomology 42: 1 – 42.

Evans, H.E. 1950. A taxonomic study of the Nearctic spider wasps belonging to the tribe Pompilini (Hymenoptera: Pompilidae). Part I. Transactions of the American Entomological Society 75: 133 – 270.

Evans, H.E. 1951a. A taxonomic study of the Nearctic spider wasps belonging to the tribe Pompilini (Hymenoptera: Pompilidae). Part II. Transactions of the American Entomological Society 76: 207 – 361.

Evans, H.E. 1951b. A taxonomic study of the Nearctic spider wasps belonging to the tribe Pompilini (Hymenoptera: Pompilidae). Part III. Transactions of the American Entomological Society 77: 203 – 330.

Evans, H.E. 1953. Comparative ethology and systematics of spider wasps. Systematic Zoology 2 (4): 155 – 172.

Evans, H.E. 1966. A revision of the Mexican and Central America spider wasps of the subfamily Pompilinae (Hymenoptera: Pompilidae). Memoirs of the American Entomological Society 20: 1 – 442.

Evans, H.E. 1997. Spider wasps of Colorado (Hymenoptera, Pompilidae): an annotated checklist. Great Basin Naturalist 57 (3): 189 – 197.

Goulet, H. and Huber, J.T. (eds.) 1993. Hymenoptera of the world: an identification guide to families. Agriculture Canada, Ottawa, Ontario. Available from the Entomological Society of Canada at http://www.esc-sec.ca/aafcmono.html

Poole, R.W. and Gentili, P. (eds.) 1996. Nomina Insecta Nearctica Volume II. Entomological Information Services, Rockville, Maryland.

Krombein, K.V., Hurd, P.D., Smith, D.R., and Burks, B.D. 1977. Catalog of Hympenoptera in America North of Mexico Vol. II (Aculeata). Smithsonian Institution Press, Washington, DC.

Pitts, J., Wasbauer, M.S., and von Dohlen, C.D. 2006. Preliminary morphological analysis of relationships between the spider wasp subfamilies (Hymenoptera: Pompilidae): revisiting an old problem. Zoologica Scripta 35: 63 – 84.

Pitts, J., von Dohlen, C.D., and Wasbauer, M.S. The Pompilid Project.
http://www.usu.edu/pompilidweb /default.htm (Please note that at the time of writing – December 2011 – the taxonomy of this website differs from that presented in Pitts et al 2006. The latter publication is considered more authoritative.)

Townes, H.K. 1957. Nearctic spider wasps of the subfamilies Pepsinae and Ceropalinae. Bulletin of the United States National Museum 209: 1 – 286.
Shimizu, A. 1993. Phylogeny and classification of the family Pompilidae. Tokyo Metropolitan University, Bulletin of Natural History 2: 1 – 142.

Vardy, C.R. 2000. The New World tarantula-hawk wasp genus Pepsis Fabricius (Hymenoptera: Pompilidae). Part 1. Introduction and the P. rubra species-group. Zoologische Verhandeligen Leiden 332 (29): 1 – 86.

Wahis, R. 1986. Catalogue systematique et codage des hymenopteres pompilids de la region Ouest- Europeene. Notes Fauniques de Gembloux 12: 1 – 91.