The adult is black, with yellow hairs at the back corners of its head, and is 4–5 mm long.

The larva is white, about 5 mm long, and lives in decaying wood.

The Finnish name is "kuolemankello", literally the "clock of death", which comes from the sound resembling the ticking of a clock, made by the male striking its head against the surface of the wood in order to attract a mate.

[1] It is the most destructive insect of buildings in Finland, where it survives the long winters in below-freezing temperatures.

[2] Because the larva lives in decaying wood, its presence indicates moisture damage.