This culprit is almost certainly the powder post beetles, Lyctus brunneus. This insect attacks the sapwood of wide pored hardwoods such as oak provided the sapwood has sufficient starch content (greater than 3%). Thus, it is clearly evident that Lyctus is a much specialised insect and has very specific requirements, especially in relation to starch. Indeed, it is the starch content of potentially susceptible hardwoods which make them susceptible to attack.
It should also be noted that as the wood ages the starch content declines due to bacterial action, etc., so that after around 10-15 years starch levels drop so that infestation/activity is no longer possible. Furthermore, given the special requirements of the insect it is not going to infest the normal old hardwood (if any) and softwoods in the house.
Adult beetles usually emerge from the infested wood between May – September. They can fly well and are attracted to light at night; during the day they hide in cracks and crevices. Beetles can often be seen emerging from infected wood and can be collected for identification. The adult beetle is dark brown in colour, somewhat elongate, 5 – 7mm in length and relatively flat.
Given the very special requirements of the insect and the wood it attacks (newly converted wide pored hardwoods where there is sufficient starch content), then most properties will not contain such timbers except where they are introduced to form a new hardwood floor, etc. Thus it is extremely unlikely that the insect will fly into a property where such susceptible timbers have just been laid. It is almost inevitable that the insect is introduced with the wood already infected; this occurs where such wood may be stored, i e, timber yards, furniture manufacturers.
The insect seems to appear in cycles I have not Â seen no significance signs of Lyctus for nearly 20 years but in the last few yearsÂ there have been Â reportsÂ received, and we are aware of numerous other cases reported.