Western Pest Services - Pest Library - True Powderpost Beetle

Pest Library

True Powderpost Beetle
Various Scientific Names

Class:

Insecta

Order:

Coleoptera

Family:

Lyctidae

Size:

True powder post beetle (lyctid) adults are 1/32 to 1/4 in (1-7 mm) long, depending on species. Larvae are up to 1/4 in (6 mm) long.

Characteristics:

Adult has a long, narrow, flat body with sides almost parallel; head and often jaws can be seen in top view; antennae with 2-segmented clubs; wing covers are often with rows of hairs. Larva is C-shaped, with enlarged thorax, short 4-segmented antennae, and legs with long claw.

Color:

Adult true powderpost beetle is reddish brown to black. Larva is nearly white.

Droppings:

True powder post beetles (lyctids) produce fine, powdery frass containing no pellets or wood fragments.

Geographic Range:

Around the world; about 11 species in the United States.

Comparison with other species:

Larvae of these lyctids produce a very fine, powdery frass in their galleries. Frass of anobiids and bostrichids is more coarse, not as "powdery", and contains pellets or fine wood fragments. Flat bark beetles have (mostly) long, threadlike antennae. False powderpost beetles (botrichids) are usually cylindrical, with rasp-like teeth, the head not easy to see from the top. Deathwatch beetles (anobiids) have a hood-like prothorax which hides the head from above, antennae with the last 3 antennal segments lengthened or expanded. Bark and ambrosia beetles are cylindrical, with antennae elbowed and clubbed. Pinhole borers and ambrosia beetles are cylindrical, with the antennal club large, flat, 1-segmented.

Habitat:

True powderpost beetles inhabit the sapwood of hardwoods, such as oak, hickory, ash and other natives (as well as tropical species, such as bamboo), that is usually less than 10 years old, with a wood moisture content of about 10-20%.

Food:

True powderpost beetles are a wood destroying insect and eat wood cell contents: mostly starch, with some sugar and protein.

Biology:

Adult powderpost beetles (lyctids) are active at night, fly well, and are attracted to light. Female lays (15-50) eggs in exposed wood pores, cracks and crevices, but never on wood that is painted, polished or waxed. The larvae tunnel in sapwood, along the grain, packing their tunnels loosely with very fine, powdery, flour-like dust. After several molts (2-9 months), the mature larva bores back to near the surface to build a chamber and pupate. The adult bores out to the surface to exit, and mates, doing very little feeding. Development time from egg to adult is 9-12 months, but can be as little as 3-4 months, or as long as a few years.

Invasion:

Eggs and larvae enter via unfinished infested wood during seasoning or storage.

Damage:

Lyctids attack lumber and manufactured products; also structural timbers, although hardwoods are not often used today for this purpose.

Detection:

Round exit holes, diameter 1/32-1/16 in (0.8-1.6 mm)
Piles of very fine powdery dust, which falls easily from holes, as it is not packed tightly in.
Presence of emerging adults during late winter/early spring (then eggs are laid, and larvae begin to bore through the wood.)