In Britain some 10 species of Hydropryche may be encountered. Most species live in clear, fast flowing water. These are rare in the low parts of Europe, including the low parts of Engeland. Only one species prefers slow flowing water and is common in Europe's lower parts: Hydropsyche angustipennis. The frontwing measures 8 to 11 mm, giving the animal a wingspan of 18 to 30 mm. The animal is brown to dark brown with some vague and small yellow or whitish markings. The antennae are longer than the body is and clearly ringed. The wings end in a rather sharp angle. Just like in the other members of this Caddis-fly family there are no ocelli (secundary eyes).
Adults of Hydropsyche angustipennis are on the wing from April to September. The species is double-brooded. While depositing the eggs females often go into the water entirely. They stay close to the bank and make a little sheet on the lower side of a stone underwater in which the eggs are deposited. The larvae do make a case of very small stones, but they don't take the case with them like most other Caddis Flies. Usually they make a little net, which is hold out of the case to catch small particles, including small animals and plants. But sometimes they leave their case to eat algae on nearby stones or to hunt for small animals. The larva pupates in it's stone case.
Hydropsyche angustipennis prefers slow flowing water with a stoney of grainy soil. It is common in the lower Parts of Europe, such as parts of England, the Low Countries, Northern Germany and most of Poland.