Control of timber pests

From the descriptions of the different timber pests it will be apparent that, in northern Europe, the only insects that warrant drastic measures are the house longhorn beetle (Hylotrupes bajulus), which causes trouble in some countries, and in certain cases the common furniture beetle (Anobium punctatum) and the powder-post beetles Lyctus spp).

In attempting to control timber pests the difficulty is that the larvae, which account for by far the largest part of the population, are well protected inside the timber. They can be treated with gas or heat which penetrates the timber, or by spraying large enough quantities of insecticides.

Pests of timber can also be controlled by treating the surface of the wood with a contact insecticidal powder so that the beetles are killed when they emerge, and before they can mate and lay eggs. In many cases this would not be a very practical method because the timber would have to be treated over a period of several years owing to the long and varying duration of larval development.

For gas treatment the substances used are cyanide or methyl bromide. These gases have the ability to spread rapidly and to penetrate the timber. When the attack takes place in a house all openings (doors, windows, etc.) must be tightly closed before the treatment is started.

Smaller objects, such as furniture, can be taken away and treated in a gas chamber.

No insect can survive a temperature of 55° C for over half an hour and this fact can be used in the treatment of timber pests. Provided they can withstand the heat small objects can be put in an oven at the appropriate temperature, in a steam bath (sauna) or in a carpenter’s drying oven.

Roof timber can be treated with heat by piping warm air under pressure into the relevant space.

Treatment of infected timber with insecticidal liquids will normally provide the best answer to the problem. Numerous preparations of this kind are available on the market. It is essential that the timber should take up as much of the liquid as possible, and apart from spraying one can also inject the insecticide using a hypodermic syringe. It should, however, be noted that the wood worm holes show where adult furniture beetles have already emerged. Even so it may be worth injecting them as the liquid may then reach neighbouring holes containing live larvae.

Treatment of timber pests, particularly the house longhorn, is often such a serious matter that it is really advisable to seek professional advice, either from a government agency or from a commercial firm specializing in pest control.

In some parts of Europe houses can be insured against the attacks of the house longhorn and if an insured house is at- tacked the insurance company has to undertake the necessary repairs and control measures without cost to the owner. Even though the responsibility lies with the insurance company it is nevertheless advisable to watch for the house long- horn because it invariably causes great inconvenience if the attack is widespread and a comprehensive programme of eradication has to be carried out.