Thatch is a very old roofing material that is still popular in some places. It not only blends well with the countryside but it also provides excellent insulation. As a result the house longhorn beetle (Hylotrupes) is unable to establish itself in the roof space below a thatched roof, which will not be warm enough for it during the summer.
However, one of the disadvantages of thatch is that it may be attacked by a variety of animals.
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
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.