( Latin: Family Siricidae)
Two of the commoner wood wasps in European forests are the horntail, Urocerus gigas, and the related Sirex juvencus. Adult wood wasps are active on warm, sunny days, when they search for freshly felled or diseased trees. The female has a large ovipositor at the rear end, with which she bores through the bark and lays eggs in the wood, one or two in each hole. The presence of fungi in the tree probably makes the wood more digestible for the larvae. At any rate, when the eggs hatch the larvae start to feed, gnawing their way through the wood. Under normal conditions they are fully grown in 2-3 years, but if conditions are unsuitable, as when the wood is too dry, then the development my take much longer.
Wood wasps only lay eggs in trees that still have their bark, so they are unlikely to enter a house, except in timber already infested. It would, in fact, be possible to buy furniture containing these larvae.
There is no risk of these insects spreading in the house, and it is very unlikely that they will be present in such numbers as to weaken the furniture. However, they may well cause damage when they emerge as adults. They can, for example, gnaw through floor boards and floor coverings or through roofing felt, or even lead sheeting (p. 163).
In some places wood wasps cause considerable damage in forests. This is why timber exported to Australia has to be guaranteed free from wood wasps.
These insects have a rather frightening appearance but in fact they never attack man and do not sting.