This is one of the largest beetles in North America and is common is western states, with Ergates spiculatus the more common of the two species in the genus. It feeds on only dead trees, the females depositing eggs on the bark shortly after a conifer dies. The larva may require 5 years or longer to complete its development and become the adult beetle, giving it plenty of time to end up in lumber salvaged from trees killed by fires. It is not uncommon, then for these enormous beetles to emerge from pine boards such as wall studs or sub-flooring, easily boring through any other materials between them and the outside world. They cannot re-infest structural wood, but large numbers may cause loss of structural integrity in load-bearing wood. They also cause large emergence holes that can disfigure wood materials and their mere presence is terrifying to most homeowners. The large feeding galleries they create in standing timber makes that tree less useful for lumber.
These are one of the many beetles very important in the decomposition and recycling of dead trees, so they provide great benefit to forests. If they are emerging within a structure the best policy is to allow the problem to run its course, since there normally will be only one or a few of them in the wood. The emergence holes can then be repaired and no re-infestation can occur.