Animals in timber

Timber is in many ways a remarkable material, and an understanding of its nature is essential for those who wish to use it correctly. Under certain conditions timber is one of the most durable materials known to man. In Norway, for example, timber churches built about 1000 years ago are still in use. On the other hand, when conditions are different timber may disappear without trace in a few years, destroyed by a variety of animals or by fungus

It is a perfectly natural process that dead trees not only accumulate, but are broken down by other organisms, and it is only when we want to preserve the timber that we regard the process as injurious.
Timber is, in fact, very poor in nutrient, and there are only a few organisms which digest its principal constituents, which are lignin and cellulose. The bacteria and fungi which live on wood produce digestive enzymes which are able to break down the lignin and cellulose to substances, such as various sugars, which can be absorbed as food.

A few insects which feed on timber secrete the same kinds of digestive enzymes in their gut (this applies, for example, to the larvae of the house longhorn beetle), but the majority have a different method, for they have established an association with micro-organisms which help to break down the wood. Finally, there are some species, such as the powder post beetles, which are dependent upon the presence in the wood of starch or sugar.