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Powderpost beetle

Lyctinae and related subfamilies

Identify and monitor first

Establishing whether the infestation is active, and whether the wood is hardwood rather than framing, decides everything that follows.

Scientific name
Lyctinae and related subfamilies
Size
2–7 mm
Group
Wood-destroying beetles
Identification confidence
Identifiable with care

Identification confidence. The flour-fine frass is the separator from drywood termites and is checkable with a fingertip.

Subterranean termite mud tube compared with drywood termite frass pelletsTwo kinds of termite evidence. On the left, a subterranean termite mud tube: a pencil-width column of packed soil running up a foundation wall from the ground. On the right, drywood termite frass: hard pellets about one millimetre long, six-sided in cross-section with concave faces, which collect in small piles beneath tiny kick-out holes. Mud tubes mean subterranean termites; pellets with no mud tubes mean drywood termites.Subterranean: mud tubepencil-width, soil, on foundationDrywood: frass pellets1 mm, hard, six-sided
  1. The frass is extremely fine and talc-like, flowing freely like flour when disturbed — this is decisive against drywood termite pellets, which are hard and six-sided.
  2. Exit holes are small and round, 1 to 2 mm, resembling shot holes in the wood surface.
  3. Adults are small, narrow, flattened beetles 2 to 7 mm, reddish-brown to black.
  4. Damage is confined to hardwoods with large pores — oak, ash, hickory, walnut, and bamboo — and does not occur in softwood framing.

2–7 mm body length

Diagnostic diagram, not a photograph. The features are described in words above.

How to recognise it

These are the features that identify a powderpost beetle. Each one is described in words so the identification works without the diagram.

  1. The frass is extremely fine and talc-like, flowing freely like flour when disturbed — this is decisive against drywood termite pellets, which are hard and six-sided.
  2. Exit holes are small and round, 1 to 2 mm, resembling shot holes in the wood surface.
  3. Adults are small, narrow, flattened beetles 2 to 7 mm, reddish-brown to black.
  4. Damage is confined to hardwoods with large pores — oak, ash, hickory, walnut, and bamboo — and does not occur in softwood framing.

What it leaves behind

  • Fine flour-like powder beneath small round holes in hardwood flooring, trim, furniture, and cabinetry.
  • Fresh powder that reappears after cleaning, which indicates active infestation rather than old damage.

Why an infestation persists

Females lay into the open pores of hardwood, so only hardwoods with large vessels are susceptible and softwood framing is not at risk. Infestation usually arrives in the wood itself — in flooring, trim, or furniture — and the life cycle can take a year or more, which is why damage appears well after installation. Determining whether an infestation is still active matters more than the damage already visible.

Where it occurs

Throughout the United States.

Where to look for it

  • Hardwood flooring, trim, and cabinetry, checking for fine powder beneath 1–2 mm round holes.
  • Unfinished undersides of hardwood furniture and the backs of drawers.
  • Bamboo items, which are frequently affected and often overlooked.
  • Hardwood joinery in older buildings, particularly oak.
  • Sweep the powder away and mark the date — fresh powder within a fortnight indicates an active infestation rather than old damage, and that single test decides whether anything needs doing.

When you see it, and why

Adults emerge mainly in spring and early summer, which is when new exit holes and fresh powder appear. The life cycle can run a year or more, so damage frequently becomes visible long after the wood was installed — and the infestation often arrived in the timber itself rather than colonising the building. Lower indoor humidity slows development, which is why the same flooring can be active in a damp property and dormant in a dry one.

What getting the identification wrong costs you

Confusing this with drywood termites sends the response to the wrong species, the wrong timber, and potentially to whole-structure work that is not needed. The texture test settles it: powderpost frass is flour-fine and flows freely; drywood termite frass is hard, gritty, six-sided pellets. There is also a structural reassurance worth having — powderpost beetles attack only large-pored hardwood, so softwood framing is not at risk from them.

What prevents it

  1. Reduce indoor humidity, since low moisture content in wood limits development.
  2. Use finished or sealed hardwood, which blocks egg-laying into open pores.
  3. Inspect unfinished hardwood and bamboo items before bringing them in.

Commonly confused with

Drywood termite Incisitermes spp. / Cryptotermes spp.

Fecal pellets are the defining evidence — hard, elongated, roughly 1 mm, six-sided in cross-section with concave faces, and they range from pale cream to dark brown regardless of the wood colour.

Sources

Every claim on this page traces to one of these.

  1. US Environmental Protection Agency Tier 1. Pesticides.
  2. National Pesticide Information Center Tier 1. National Pesticide Information Center.
  3. Cooperative Extension System Tier 2. University extension entomology resources.
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