Many insect species are able to use wood as a food source. In doing so they can cause serious damage to timber by tunnelling into standing trees, freshly felled logs or wet decaying timber. A very small number of beetles are able to attack timber in the more or less dry conditions found in buildings.
These beetles all have a similar life cycle, although there are variations in the length of each stage in the life cycle, the type of wood attacked, and the extent and type of damage caused. Eggs laid by adults on timber surfaces, or in cracks in the timber, hatch to release very small grubs (larvae) which bore into the wood, feeding on the cellulose, lignin and other wood components, and creating a distinctive network of tunnels. The larvae of most wood-boring insects fill the tunnels with excreted wood pellets known as bore dust or frass. The size, shape and cross-section of the tunnels, and, to a lesser extent, the characteristics of the bore dust, are useful in identifying the species of insects.
After a period of one or more years’ feeding, the larvae undergo a metamorphosis within the timber, passing through a pupal stage before changing into adult form. These adult beetles then emerge, leaving the familiar ‘woodworm’ exit holes in the surface of the timber. The beetles do not themselves cause further damage, but, after mating, females often re-infest with their eggs in timbers near to those from which they have emerged; they may also fly or crawl some distance in search of suitable timber on which to lay their eggs. Damp conditions generally encourage infestation by most insects, and, in particular, deathwatch beetle and common furniture beetle.
The principle insects’ species attacking timber in buildings are:
Common furniture beetle
Commonly referred t as ‘woodworm’; this insect can attack the sapwood of all softwood and European hardwood timbers, such as oak and elm, in buildings throughout Britain. As shown here:
House longhorn beetle
This insect is not common in the UK except in certain areas of north Surrey. It is principally found in roof timbers where it attacks the sapwood of exclusively softwood timbers, often resulting in structural weakening. As shown here:
Deathwatch beetle common throughout the southern half of the United Kingdom; it is found less frequently in north of England. As shown here:
Wood-boring weevils attack only damp, fugally decayed timber. Although they may increase the rate of deterioration by their tunnelling, they are not a primary cause of timber deterioration. Damp joist ends and the backs of skirting boards on damp walls are commonly attacked.
At Dampshield our team use a specialist Sovereign treatment that involves applying Sovereign Sovaq FLX F/1 under pressure to all accessible timbers. This includes timbers such as roofs, floors and stairs. Substantially weakened timbers must be placed with pre-treated timber where necessary.