Woodworm and Death Watch Beetles

A number of insects cause decay of timber in our buildings. The best known are woodworm and Death watch beetle. They lay their eggs on the surface of the wood, the hatching larvae tunnel in the timber and create galleries. The tunnelling causes structural damage to the timber.

Often the insects’ activities are not significant, as the timber species may dictate that only the sapwood is consumed, which may only be a small cross-section of, for instance, a floor joist. The adult insects can be seen on the timbers during the flight season (April to August) and dust (frass) may be seen on the floor beneath infected timbers as the insects emerged from the wood.

The solution
If an active infestation is found then the circumstances surrounding the attack need to be considered carefully. For instance, does the timber have high sapwood content, what species of timber is it, how wet is the timber, what would be the cost of replacement rather than treatment? More often than not infestations only require changes in the environmental conditions to reduce the moisture content of the wood, for instance, increasing ventilation to a roof void. The infestation will eventually die out as the timbers dry. In preparation for the application of preservatives the timbers should be cleaned down to remove any excessive dust and debris. Treatments using water based insecticides are very common and are generally successful and cost effective. Chemicals are often applied by low pressure spraying but some insecticides can be applied by “fogging” or are brushed on.