after about a month. The newly hatched larvae are tiny and chew their way into the timber, feeding on the wood. Their growth is slow and it may take from two to ten years, or even more, for them to reach their full size. At this stage they pupate in a chamber close to the wood surface, and either emerge through a newly created hole after twenty to thirty days, or else emerge in the following spring (about eleven months later). Ecology In buildings, deathwatch beetles infest old oak timbers, especially those that have been the subject of fungal decay, usually by the fungus Donkioporia expansa. This fungus affects damp timber, often gaining entry where rafters or joists are embedded in stone walls, or in the vicinity of leaking roofs or overflowing gutters. It is not the adult insects that cause structural damage to the building, but rather their larvae tunneling through the wood. Wood is difficult to digest, but as long as the wood has been softened by fungal decay, the enzymes in the guts of the larvae are able to digest the cellulose and hemicellulose forming the cell walls; this enables the larvae to make use of the protein, starch and sugars found within the cells. The steely blue beetle (Korynetes caeruleus) is a predator of the deathwatch beetle and of the common furniture beetle (Anobium punctatum). The adult female blue beetle lays her eggs in the exit holes made by the emerging borers, and the carnivorous larvae wander through the galleries made by the wood-borers, feeding on their larvae. The adult deathwatch beetles are weak fliers and may run over the surface of the timber, rather than fly. They are sometimes caught by spiders, their silk-encased husks being found on webs. Host selection An adult female deathwatch beetle is short-lived (1–2 months) and must find a suitable host in which to lay her eggs relatively quickly. She is capable of using odour to locate wood that has been decayed by fungi, which provides an excellent host. When selecting a host, old wood (more than a century old) is favoured. Trees with deep crevices are also favoured, as they provide a dark safe shelter for the eggs. Communication A deathwatch beetle communicates by hitting its head on a substrate to create a noise, a method called tapping. Males and females differ in that males usually tap first, and