A caddisfly, (Trichoptera), adult. Photo by Drees.
Common Name: Caddisfly
Scientific Name: Varies
Order: Trichoptera
Description: Adult caddisflies resemble small moths with wings held tent-like over their back when at rest. They have long hair-like antennae. Most species are small (usually 1/4 inch or less) and are dull colored. However, some species are more brightly colored. Immature stages or larvae superficially resemble hairless caterpillars. They often have elongated fleshy gills on the underside of the abdomen. Most larvae have a pair of hooks on the (anal) prolegs on the last abdominal segment. Many of them fashion cases of plant material, sand, pebbles or debris in which they live.
There are many species of caddisflies. Adults can be confused with small moths (Lepidoptera) but they never have coiled “siphoning” mouth part as do moths, and they usually have long, hair-like antennae. The larvae may be confused with a few aquatic moth species (Lepidoptera), some beetle (Coleoptera) larvae or even dobsonfly larvae (Neuroptera: Corydalidae). The larvae of caddisflies can be distinguished by the claws on the thoracic legs and the anal prolegs.
Life Cycle: Adult caddisflies are short lived and spend most of their time mating or laying eggs. Females lay eggs on the edge of the water or by females dipping their abdomen into the surface of the water. Caddisfly larvae develop through four stages (instars) over several months or even a year. Pupation is almost always aquatic. There is usually one generation per year.
Habitat and Food Source(s): Adults do not feed and have vestigial mouth parts; larval stages have chewing mouthparts. Immatures are found in water, usually in flowing water. Larvae are scavengers, herbivores or predaceous. They can spin silk and use it to form nets to strain material from the water to eat or to form cases in which to hide. The type of case or use of silk for a web depends on the species. Pupal cases are often attached to objects. Adults generally fly quickly from the water. Mating takes place on the ground or vegetation. Adults are commonly found near lights at night or on foliage near water.
Pest Status, Damage: No damage, generally innocuous; adults are attracted to lights and occasionally abundant enough to be noticed; immature stages are aquatic, where they are important part of the diet of fish; medically harmless.
Management: None, not considered a pest.
For additional information, contact your local Texas A&M AgriLife Extension Service agent or search for other state Extension offices.
Literature: McCafferty 1981.