Adults are 3/16" to 5/16" in length; larvae - 3/8".
The beetles are dark reddish brown and have yellowish scale-like hairs on the upper body and wing cases. The larvae are a creamy white hook-shape covered in erect golden hairs with dark brown jaws on its head.
After mating, the female lays 3-4 eggs clustered in cracks of rough wood surfaces. They are whitish, oval shaped and she lays between 40 and 60 during her life. The eggs hatch within two to five weeks.
The larvae pupate just below the surface of the wood. The adult emerges in early summer by gnawing through the surface and leaving the characteristic exit holes.
In its natural environment the insect lives in the dead wood of several species of hardwood trees where fungal decay has set in.
Within buildings the insect occurs almost entirely in old hardwood, in particular large oak timbers.
The larvae do the most damage, as they tunnel in the wood for between five and ten years.