Caddisflies (Order: Trichoptera)
The Trichoptera, or Caddisflies, are an order of insects, somewhat related to moths, and of which there are just under 200 species in the British Isles. The name means 'hairy-winged', and indeed they differ from moths in having hairs rather than scales on their wings, amongst other differences.
Main characteristics of Caddisflies
- Adults of most species are nocturnal and are attracted by light
- Most species hold their wings along their bodies when at rest, with their antenna pointing forward
- The adults have two pairs of wings of which the hind one is slightly shorter
- The adults of most species have atrophied (wasted away) mouthparts and feed is restricted to sucking nectar and other plant juices.
- The undergo a complete metamorphosis
- The eggs are normally laid in or near water in a jelly like substance
- The females of many species crawl in to the water to lay their eggs
- The larvae of all the British species, except one, are aquatic and breathe using gills
- Whilst some larvae are free-living, others construct various different structures for protection and camouflage
- Some species have larva that are carnivorous, some are herbivorous, whilst others still are omnivorous
- Those species which construct a larval case, usually pupate in the case which has been attached to a support. Free living larva construct a shelter for pupation
- The pupa possesses a strong pair of mandibles to bite it's way out of the shelter, and having risen to the water surface, and uses a pair of modified legs to reach land and emergence takes place
- The larva have six well developed legs, and at the end of the abdomen, a pair of prolegs bearing hooks, which distinguish the order
For collecting the adults, other than those attracted by light, a net is needed, whilst a pond net is used for collecting the early stages in water. Adults can also be found by using a sweep net through suitable vegetation, or by searching structures near water. Larger species can be pinned and set in the way Lepidoptera are preserved, but smaller species may be better preserved in a suitable liquid.
Species found in still water are usually easy to rear through to adulthood, but those from running water are more troublesome.
Essential reading from the Amateur Entomologists' Society
The Beginner's Guide to Caddis
The AES published the Beginner's Guide to Caddis by Ian Wallace in the February 2003 issue of the Bulletin. It is available here as a free download.
Related links: Caddisflies (Order: Trichoptera)
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