To treat an infestation of powderpost beetles, an insecticide containing permethrin, cypermethrin or cyfluthrin needs to be either painted or sprayed liberally onto the infected wood. The exterior of the wood should be completely saturated.
The insecticide only kills emerging adult powderpost beetles. The larvae reside deep in the interior of wood, where the insecticide does not reach. Several applications of insecticide are necessary to destroy an infestation. It is best to apply the insecticide in the spring when most larvae mature into adults. If the infestation is extensive or difficult to reach, professional fumigation becomes the only option.
An infestation starts when a female powderpost beetle lays eggs that drop deep into cracks and holes in wood. Powderpost beetles do not lay eggs on finished wood, but infestations can occur in finished wood if the eggs were laid before the wood was finished. Before applying insecticide to a finished surface, first test the insecticide on a small area to ensure it does not ruin the finish. For smaller wooden items, it is possible to completely kill an infestation by keeping the wood at 0 degrees Fahrenheit for several weeks or by heating the wood to 150 degrees Fahrenheit for 4 hours.