You will only see holes that have been made as they exit the wood inside or outside of your home. Problems are often only noticed once a survey has been completed at your house. The adult form is a naturally occurring beetle that lays eggs on dead trees, normally pine but other types of wood in a greater state of decay can be chosen as well.
The adults themselves do not feed on wood but on pollen. As in most insects the adults main function is to mate and to lay eggs. The beetles coming across timbers in your home treat it the same as they would a dead tree and will lay eggs. The eggs will hatch into small grubs that bore into the wood, this is what causes the damage. Too much of this boring will lead to the weakening of the timbers.
The larvae can remain in the wood for up to 6 years but usually emerge in under 3 years. The emerging date is often 6 years in buildings due to the artificial conditions in properties affecting the lifecycle. When the larvae is ready to pupate it bores its way to near the surface of the timber and pupates. The pupal stage refers to when an insect transforms from a larvae to its adult form.