Evidence signature
Tiny round holes with flour-like powder accumulating below unfinished or stored wood.
The strongest identification comes from several independent observations that agree: the physical sign, its exact scale, where it accumulates and a companion clue. One isolated mark is rarely enough.
Most useful evidence
Frass and pellets, Holes and openings, Larvae and grubs, Damage and gnawing.
Typical locations
Wood and furniture, Attic and roofline, Basement and crawlspace.
Common timing
Seasonal, Any.
Supporting context
Wood.
What supports this identification
- Very small round exit holes
- Fine flour-like powder
- Fresh powder returns after cleaning
- Activity tied to a specific wood item
What points away from it
- Large oval old-house-borer holes
- Uniform termite pellets
- Mixed carpenter-ant shavings
Measure hole diameter and rub a small detached sample of debris between gloved fingers only if safe to assess powder fineness.
A safe first response
Isolate movable items and avoid treating structural wood without identification.
Preserve a clear photograph with scale before cleaning when that can be done safely. Avoid broad pesticide applications until the target and exposure route are understood; an indiscriminate treatment can scatter activity, contaminate surfaces or obscure the evidence.
When to bring in a professional
Seek a wood-pest professional for active structural or widespread evidence.
Common lookalikes
Old house borer
Hylotrupes bajulus
Larger oval exit holes, coarse packed frass and feeding sounds in softwood framing.
Drywood termite
Kalotermitidae
Uniform hard pellets in small piles directly below tiny wood openings, often recurring after cleanup.
Carpenter ant
Camponotus spp.
Coarse mixed wood shavings below a slit or crack, often with large ants and moisture-damaged wood nearby.
Direct comparisons
Side-by-side decision
Powderpost beetle vs. old house borer
Exit-hole diameter and frass texture are decisive: powderpost signs are tiny and flour-like; old-house-borer signs are larger and coarser.
Open comparison
Side-by-side decision
Termite pellets vs. powderpost beetle dust
Termite frass remains distinct pellets; powderpost frass behaves like fine flour around tiny round exits.
Open comparison