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© Queensland Government
© Queensland Government
The powderpost beetle is one of the most significant timber borers found in Queensland. The larvae can reduce susceptible timber to a fine, flour-like powder.
The beetle attacks seasoned timber, causing significant structural damage and considerable financial loss. For property owners and manufacturers, prevention is less costly than treatment.
- Lyctus discedens (the small powderpost beetle)
- L. planicollis
- L. parallelocollis
- Tristaria grouvellei
- Minthea rugicollis (Malayan powderpost beetle, now established in Queensland due to presence in imported rainforest hardwoods from South-East Asia
- Adults are flat, up to 7mm long, dark-brown, and shiny.
- Adults have a distinct head and the terminal segments on antennae appear clubbed.
- Larvae are cream-coloured with brown head and jaws and 3 pairs of small jointed legs.
- Larvae, on hatching, are about 0.5mm long with a straight body that later becomes C-shaped.
- Widespread in Queensland's tropical and subtropical climates.
- Attacks only the sapwood of susceptible hardwoods and not softwoods.
- Occurs in timbers that contain enough starch to nourish the developing larvae.
- Heartwood is never infested, although adults may emerge through it.
- Occurs in logs or sawn timbers drying at the sawmill.
- May not be noticed until the timber is in-service and adults emerge.
- Contains galleries packed with fine flour-like powder.
- Infested areas may be reduced to powder within a shell of wood, perforated by exit holes.
- Small piles of smooth, flour-like powder may be found outside the timber.
- May occur anywhere that susceptible timber has been used (e.g. in subfloor areas, living space, roof space, or in furniture and artefacts).
- Re-infestation is common for up to 5 years after tree-felling, until the food resource is depleted.
- In new houses, exit holes may appear in the lining materials (e.g. in plasterboard and panelling) and joinery. These holes are made by adults emerging from the hardwood framing underneath
- Female beetles lay up to 70 eggs in sapwood containing starch, which is essential for larval growth.
- Eggs hatch after 14 days and the larvae create tunnels along the wood grain as they feed.
- Larvae take from 2–12 months to mature, depending on temperature, humidity and food supply.
- Full-grown larvae tunnel towards the surface and create oval cells within which they pupate.
- Mature beetles emerge after 2–3 weeks through circular holes (1–2mm diameter), creating small piles of fine flour-like powder on the timber surface.
Monitoring and action
- Avoid damage by having the supplier remove sapwood from susceptible timber species or by using non-susceptible timber.
- Where damage is not structural, treatment may not be needed except to repair the timber's appearance.
- Last reviewed: 12 Dec 2018
- Last updated: 12 Dec 2018