Trichoptera

Order

TRICHOPTERA
(Greek, thrix = hair; pteron = wing)

Description

Adult caddisflies are soft bodied and resemble moths. The order Trichoptera is closely related to the order Lepidoptera. The adult insects have large compound eyes with two or three simple eyes (ocelli). Antennae are long and composed of short, straight segments (filiform). Mouthparts are reduced and adults are incapable of consuming solid food. They can ingest nectar or water but often do not feed at all. Two pairs of wings are held at rest in a position which resembles the two sloping sides of a house roof. The wings may be hairy or scaled. Body colour is grey or brown and resting insects are extremely well camouflaged.

Life Cycle

The larval stages are aquatic. Eggs are laid in sticky masses attached to twigs or rocks in the water. On hatching the larva  may either build a case in which it lives or remain naked and build a conical net which is used to capture food. Case building larvae are mostly vegetarians and feed on detritus or may graze upon water plants. But others prey on small fresh water animals. Net building larvae are purely carnivorous. Net spinners are restricted to flowing water, but case makers frequent still water. On maturity, the larva pupates either within a cocoon or only as a pupal case protected by silk strands through which water flows. The pupa has free legs and large mandibles with which it chews through the cocoon or silk and swims to the surface. The pupa then splits and is used by the emergent adult as a floating platform.

Food

Caddisflies feed on fresh vegetative material or detritus. Small freshwater animal life will also be consumed.

Importance

Caddisflies are very important as a food resource for fish in freshwater streams.