THRIPS (THYSANOPTERA) OF BRITISH COLUMBIA
R. A. Cannings and G. G. E. Scudder
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Commonly called thrips, these are minute 0.6 - 5 mm long exopterygote insects, with piercing and rasping mouthparts, narrow wings fringed with long setae, and legs without claws. The mouthparts consist of a single mandible and paired asymmetrical maxillary stylets, with feeding technique. While leaf, flower and pollen sucking is common, many feed on fungal hyphae. Several unrelated groups are predators, feeding on small arthropods, especially mites and scale insects. Plant feeders can cause damage because of their sucking habit, and some act as vectors of disease, especially tomato spot wilt.
The life cycle consists of an egg stage, two active larval instars that feed, followed by two or three relatively inactive pupal instars that probably do not feed. The following adults may be winged or wingless. These adults can form a major component of aerial plankton, even if they are without wings.
Most phytophagous thrips, namely those in the suborder Terebrantia, insert the eggs into plant tissue, with the females having a well developed ovipositor. However, in the suborder Tubulifera, wherein the female lacks an ovipositor, the eggs are deposited from an external opening near the end of the abdomen and are attached to the surface of the substrate either horizontally or vertically.
Thrips exhibit haplodiploidy, wherein the males are derived from unfertilized eggs: fertilized eggs produce females. However, many species are parthenogenetic and can reproduce in the absence of males. Sexual dimorphism is often evident.
Four families have so far been recorded in Canada, with three of these (Aeolothripidae, Thripidae, Phlaeothripidae) reported in British Columbia. The family Heterothripidae has so far not been recorded in the province.
Chaisson, H. 1985. A synopsis of the Canadian Thysanoptera. M.Sc. thesis, Macdonald College, McGill University, St. Anne de Bellevue, Que. 224 pp.
Loan, C. and Holdaway, F.G. 1955. Biology of the red clover thrips, Haplothrips niger (Osborn) (Thysanoptera: Phloeothripidae). Canadian Entomologist 87:210-219.
Mound, L.A. and Kibby, G. 1998. Thysanoptera, an identification guide. Second edition. CAB International, Wallingford, Oxon, UK. 70 pp.
Nickle, D.A. 2003. A checklist of commonly intercepted thrips (Thysanoptera) from Europe, the Mediterranean, and Africa at U.S. Port-of-Entry (1983-1999). Part 1. Key to genera. Proceedings of the Entomological Society of Washington 105:80-99.
Palmer, J.M., Mound, L.A. and du Heaume, G.J. 1989. IIE Guides to Insects of Importance to Man 2. Thysanoptera. CAB International, Wallingford, Oxon, UK. 73 pp.
Stannard, L.J. 1968. The Thrips, or Thysanoptera, of Illinois. Illinois Natural History Survey Bulletin 29(4): 215-552.