The adult beetle is around 6 mm in length; females are usually larger, ranging up to 8 mm.
It is dark greyish-brown in colour, with a pattern of yellow scale-like hair patches on the pronotum and elytra.
The female lays small clusters of 3 or 4 eggs on the surface of rough wood, in cracks or just inside flight holes. The average number of eggs laid is 40 to 60.
The larvae of these beetles bore into hardwood timbers where fungal decay has occurred. From such situations softwoods may be attacked. The larva grows to a length of approximately 12 mm.
The adult beetle cannot fly and therefore when found indoors it is almost certain that the beetle has been infesting the timber since it was originally hewn.
Adult beetles emerge in infested buildings between mid-March and early June.
Under optimum conditions, the life cycle takes place in one year. However, it is variable depending on conditions, but on average is thought to be around 4 to 5 years.
A tapping noise is made by both sexes knocking their heads against the wood on which they are standing. This tapping constitutes part of the mating behaviour.
Xestobium rufovillosum occurs throughout Europe but it is extremely rare in Scotland or Ireland. Significance
Oak is the principal timber attacked but they have also been found in elm, chestnut, alder and walnut.
It is a common insect outdoors, being found in dead wood, branches or trunks of several hardwood trees where fungal decay has arisen.They can be introduced indoors via wood used as logs for fires and emerging beetles could conceivably attack wood that has fungal decay, on which they will lay their eggs.
Treatment is as for the common furniture beetle, Anobium punctatum, which consists of applying a proprietary woodworm fluid to infested timbers.
Treatment must be thorough, as woodwork that does not show flight holes may contain death watch beetle larvae as the length of the larval life may be in excess of five years.
Illustration: Xestobium rufovillosum adult.
Please note the furniture beetle is the major cause of woodworm that can lead to major financial costs if not treated.