British Insects: the families of Caddis flies (Trichoptera)


L. Watson and M. J. Dallwitz

Leptoceridae Leach

Adults. Antennae considerably longer than the fore-wings; very slender; with an elongated first segment (rarely), or with a short first segment (the first segment bulbous). Ocelli absent. Maxillary palps 5 segmented. The maxillary palps of males 5 segmented. Maxillary palps filiform, with cylindrical segments; the terminal segment and often the adjoining, fourth “segment flexible but not articulated” (Mosely and Kimmins, 1953). The scutellum without conspicuous warts.

The fore-wings (5.5–)7–13 mm long; without a median cell; with a discoidal cell; apical forks 2 (males usually with 1 and 5), or 3 (some females with 1, 3 and 5, and Triaenodes with 1, 2 and 5). The hind-wings narrower than the fore-wings to wider than the fore-wings (but always much shorter); without a discoidal cell; apical forks 1 (fork no. 1), or 2 (1 and 5).

Front tibia 0 spurred, or 1 spurred, or 2 spurred. Middle tibia 2 spurred. Hind tibia 2 spurred.

Larvae. The larvae constructing and living in transportable cases (the cases cylindrical, straight or slightly curved, of plant debris and/or fine sand or gravel). The larval case not constructed of vegetable matter arranged spirally (usually), or constructed of vegetable matter arranged spirally, open at both ends (in Triaenodes bicolor only: in that species, the larva carries its long, slender case through the water, swimming using its specially fringed and oar-like, metathoracic legs). The larvae eruciform. The right mandible without a brush of hairs on its inner surface. The thorax without a prosternal horn. The mesonotum sclerotized; entire, or divided longitudinally into two sclerites. The metanotum entirely membranous; without brushes of bristles. The metasternum with either a dense zone of stout bristles, or a transverse row of at least six. Abdominal segment 1 with retractable papillae; 8 with a lateral comb of fine spicules. The larva with the terminal abdominal prolegs fused basally, forming an ostensible tenth segment.

British representation. 31 species. Genera: Adicella, Athripsodes, Erotesis, Leptocerus, Mystacides, Oecetis, Setodes, Triaenodes.

Illustrations. • Oecetis ochracea Curtis (Ochre Caddis-fly: B. Ent. 057). • Oecetis ochracea (B. Ent. 57, legend+text). • Oecetis ochracea (B. Ent. 57, text cont.). • Wings of assorted Trichoptera. • Triaenodes bicolor: larva and case. • Mystacides, Setodes and Athripsodes: larvae and cases.

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. British insects: the families of Caddis flies (Trichoptera). Version: 29th December 2011.’.