National Oak Flooring Manufacturers Assn. Tunneling through the wood by the beetles' larvae eats away the sapwood portion of boards. When an extreme infestation occurs, the larvae can virtually destroy the wood in the infested area. Determining if an infestation is active is the key to what treatments, if any, are necessary. Many reports of powderpost beetles are erroneous.
Genuine infestations are fairly easy to spot.
Real powderpost beetles are usually first discovered when the adult eats a hole in the surface of the wood from within. The flight holes are perpendicular to the surface and tunnel walls and show a bright raw wood color. All Oak flooring grades allow the presence of pinworm holes in the face of flooring strips. These holes are in the wood before the lumber is dried and made into flooring. As the finish is applied a film is formed over the holes.