Caredrina clavipalpis

When a roof is newly thatched, whether with straw or reeds, thousands of grey- brown moth caterpillars may suddenly appear in the house.

In the wild these larvae live on grasses and reeds, and they reach the house in the thatching material. It is nearly always the fully grown larvae which appear in this way, as they wander out of the roof in the autumn to find a suitable place to spend the winter.

Occasionally they gnaw their way into various materials where they re- treat for the winter, and then pupate in the following spring and emerge as moths. The adult moths will not lay eggs again in the thatch, so the owner of the house experiences only a single generation and there is usually no need to take drastic action.

CRANEFLY LARVAE may also appear in thatch (p. 105). They normally live in damp earth, and so it is only in old, damp, mossy thatched roofs that they can thrive. They themselves do little damage in a roof that has already suffered, but it becomes more serious if rooks or other birds discover this source of food and start to pull at the thatch in order to reach the larvae.

HOUSE SPARROWS (see also p. 84) often build in thatch. They pull out the straw and make tunnels in the roof, particularly in the eaves and along the ridge. The only effective, but not very attractive, method of preventing this is to cover these areas with galvanized chicken netting.

The BEECH MARTEN sometimes finds its way into lofts (see p. 188); it does not, however, occur in Britain. It is difficult enough to proof a house against martens and particularly so when it has a thatched roof. The marten tears holes in the thatch with its claws, and the edges of the holes are therefore frayed.

RATS (see also p. 88) can also work their way through a thatched roof. In contrast to the beech marten they use their teeth and a hole made in thatch by a rat therefore has regular sharp edges.