Take care that infested wood is not introduced into the house. Existing infestations can be eradicated by treatment with a commercial wood preservative, with persistent contact insecticidal fluid, or by preservative-insecticide mixture sold for 'woodworm' control. These chemicals are made up with appropriate solvents designed to give maximum penetration of the wood and are applied by brushing, spraying or immersion. Products for household use are available from hardware stores, garden centres and retail outlets that stock household and garden insecticides. The success of insecticide treatment depends largely on the thoroughness with which the fluid is applied. Special attention should be given to any rough, unpainted or unpolished surfaces, for these are the places where eggs are laid. In addition to brushing or spraying the fluid over all surfaces, it should also be injected into the exit holes using a small syringe. After treatment all exit holes should be filled with wax, or plaster or wood-filler which can then be stained and polished. Filling the holes makes it easier to detect the appearance of any fresh holes and so decide when the infestation has ended. The best time to apply insecticide is in spring (March-May) when the insects are near the surface, just before they emerge, and so are more accessible to the insecticide. The life cycle of most wood-boring beetles lasts more than one year, so that to achieve complete eradication it is essential to repeat the treatment each year until signs of the attack disappear.