POWDERPOST BEETLE


Lyctus brunneus (Stephens)


[Coleoptera: Bostrichidae]

powderpostbeetl


Article by Bruce Gow


Adult: Powderpost beetles are 2-7 mm long. The body is cylindrical to cigar-shaped, dark brown and shiny.

Head: Antennae have 9-11 segments with a well defined 2-segmented club. Compound eyes are large and positioned on the lateral margin of the head. The mouthparts consist of mandibles for chewing with 2/3-segmented maxillary palps and 1/2-segmented labial palps.

Thorax: Two pairs of wings are present. The forewings are hardened into protective covers called elytra. The elytra are not used in flight. The elytra protect the hindwings and serve as a dorsal exoskeleton. The hindwings are membranous, fan-shaped and fold flat over the body when at rest. The pronotum is large and square-shaped. All legs are similar.

Abdomen: Cerci are absent.


Reproduction & Life-cycle:Adult females lay approximately 70 eggs during their life-time. The female bites wood and lays 1-3 eggs in the incision. The eclosion period is 6-15 days. Larvae are white and C-shaped (scarabaeiform) with large spiracles on the 8th abdominal segment. The larval stage is 2 months to 1 year and is dependent on temperature, humidity and the starch in sapwood. Mature larvae tunnel toward the surface of the wood and excavate an oval cell for pupation. The pupal stage is 12-27 days. Adults live 78-300 days.

Distribution: The powderpost beetle is a cosmopolitan pest that was originally endemic to North America.


Pest Status:Lyctus brunneus is a pest on sapwood of unfinished hardwoods, picture frames, bamboo and baskets. Adults and larvae are pests and the larvae require starch for development. Reinfestation of timber is common for this beetle.

“Not only the poisonous and aggresive bugs are pests, watch out for the ones you neglect most.” – Bruce Gow

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