The name “powderpost beetle” is a broad term used for several species of wood-destroying beetles that like to infest untreated wood that’s been exposed to humid, damp conditions.
Damage caused by these critters is the cause of more confusion than any other structure-infesting pest — an expert inspection is the best way to identify it.
Powerpost beetle larvae feed on wood cellulose, and will severely damage floor joists, girders, and other structural wood in 1-5 years. The wood they feed upon is reduced to a fine powder, which is deposited in tunnels below the surface of the wood.
Once fully developed, emerging adults will leave tiny, round holes in the wood — about 1/8″ in diameter. They will quickly mate, laying new eggs on or below the wood’s surface.