Reaching a length of 15 mm Limnephilus flavicornis is a typical representative of this big genus. The wings are yellowish brown with a variable number of brown spots. The thorax is grey. The antennae are as long as the body is. Limnephilus flavicornis flies by night only. During the day it more or less hides itself in plants or shrubs. The female deposits her eggs in one jelly-like blob on the underside of a leaf hanging over the water.
After hatching the small larvae fall into the water. Here they build their house, usually by weaving pieces of duckweed together. Larger larvae however also use shells of snails, sometimes even living snails. They do a bad job, for everything is stuck together in a very sloppy way: their house looks very disheveled indeed. Before pupation the larvae sticks his house to the stem of a plant growing out of the water. When pupation is almost finished the pupa climbs out of the water and gives birth to a new adult caddis fly.
Limnephilus flavicornis is a very common species all over Britain. It prefers standing or slowly running water though. It may be found in sweet water, but it tolerates brackish water as well. The adults are seen from May till October.