Caddis flies 2

Families on this page

Molannidae Hydropsychidae
Leptoceridae Rhyacophilidae

Molannidae family

adult caddis fly in the Molannidae family

Above is an adult in the Molannidae family. The larvae live in still water of lakes and large ponds and construct their case out of sand grains, see the drawing below. The case is a central, tapering cylinder covered by a broad, almond-shaped shield. There are only 2 British species in this family.

caddis fly case of Molanidae

Molanna angustata

Below is Molanna angustata. It is fairly widespread.

The adult has long hind legs and an forewing 10 - 12 mm long. The antennae are longer than the wings. The adults are seen from May - September.

The larva is found in sandy-bottomed lakes and slow rivers and streams.

Molanna angustata

Leptoceridae family, Long-horned caddis

Triaenodes sp. caddis fly case

The females in this family lay eggs in a jelly mass on stones and plants. The larval cases (see Triaenodes sp. above) are relatively narrow and some are slightly curved. They tend to be made of plant material or sand grains. Most of the larvae are vegetarian. The adults have very long antennae; sometimes 3 times as long as the body. There are 31 British species.

Above is Triaenodes sp., its case is similar to those in the Phryganidae family. It is 20 30 mm long, and made of plant material arranged in a spiral. The larva is an active swimmer, and its 3rd. pair of legs are very long and covered in hairs. Before it pupates the larva fixes the case to a plant. The eggs are found on the undersides of floating leaves.

Larvae in the genus Leptocercus (below) have a curved case usually made of sand grains and 11 - 17 mm long.

Leptocercus sp. adult caddis fly

Rhyacophilidae family

The eggs are stuck to the bottom of stones in streams. The larvae (below) are actively predaceous carnivorous, and found in rapidly-flowing water. Not all species in this family construct cases, and the ones of those who do tend to be rather simple and crude. There are 90 European and 4 British species.

Rhyacophilia sp. caddis fly larva

Rhyacophila sp. larvae (above) are found on the under surface of stones and fast-flowing water. They do no build a case. Fully grown larvae are 9 - 14 mm long and are green and brown. They move around quite quickly using their legs and anal appendages to hold on to stones to avoid being swept away. The larvae pupate in the late autumn in a shelter they make of small stones stuck to the underside of a larger stone. Inside this is makes a cocoon.

Hydropsychidae family, Grey Flags, Marbled Sedges

In this family the larvae and eggs are found in fast-flowing streams. The eggs are cemented to the underside of stones. There are 60 European and 11 British species.

Hydropscyche caddis fly larva

The larvae (see Hydropsyche sp. above), are very active, and when fully grown can be 10 - 20 mm long. Very young larvae do not have gills. Note that the anal appendages are large. They do not build a case, but live in a silk net stuck to the underside of a stone. The silk to make the net issues from oral glands. Inside the net there is a silk tunnel, open at the end which faces the flow of water, and closed at the other end. The larva lives in the tunnel and eats anything - animal or vegetable - that is caught in the net.

Before pupating the larva constructs a shelter made of small stones.

Adults swarm in the evening prior to mating.

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