- Size from 1/12 to 1/3 inches in length
- Are reddish-brown to black
- Body is shaped like an elongate flattened cylinder.
- Antennae are 11-segmented, with a distinct two-segmented club at the end
- Each tarsi has four segments, and tibia have spurs
- Are white, C-shaped grubs, with the thorax wider than the rest of the body
- The eighth abdominal spiracle is much larger than all the others.
- Larvae make round tunnels that are loosely packed with very fine frass that has the consistency of talcum powder, which is where the name "powderpost" comes from. This is usually the result of several generations of beetles in the same wood.
- When adults leave the wood, it is left with many small round holes that are 0.03 to 0.13 inches (0.8 to 3.2 mm) in diameter. The adults are leaving to search for a new wood source.
- Powderpost beetles usually attack only seasoned or partly seasoned sapwood of hardwoods such as ash, oak, pecan and hickory, but they will also attack bamboo, cherry, elm, persimmon, walnut and many others.
- They can attack wood with a moisture content between 6-30%. Most wood within centrally heated and cooled buildings contain enough moisture for lyctid attack.
- They will reinfest the same wood repeatedly until it is virtually useless and they may spread to other hardwoods nearby.
- Susceptible wood must have pores large enough for adults to insert eggs into, thus, most damage is restricted to the unfinished portions of sapwood.