Small round holes in crawl-space beams or subfloor, with fine flour-like powder beneath them, are the signature of powderpost or wood-boring beetles. Fresh powder means an active infestation quietly working through your structural wood.
What’s most likely going on
Powderpost and anobiid beetle larvae tunnel through wood for months or years, then emerge as adults through those 1/16-inch exit holes, sifting out the talc-fine frass. Our damp, unconditioned crawl spaces are ideal for them.
What it means for your home
Repeated generations progressively weaken flooring, joists, and framing, and because the larvae work unseen, damage is often advanced before the holes appear. Higher wood moisture is what sustains them.
What to do next
We assess how active and widespread it is, treat the affected wood, and address the crawl-space moisture that lets the beetles thrive. You can read more in our Pest Library entry on powderpost beetles, or head straight to our Powderpost Beetle Treatment service.
Reviewed by Matthew — Salty Dog Pest Control. WSDA-licensed structural pest applicator (License #101709). Veteran- and family-owned, serving Whidbey Island, Fidalgo Island, and west Skagit County.
Frequently asked questions
How do I know if the beetles are still active?
Fresh, powder-fine frass and clean new holes indicate active emergence. Old, empty holes without new powder may be inactive — we can tell the difference.
Why are they in my crawl space?
These beetles favor higher-moisture wood, so damp, poorly ventilated crawl spaces are the most common place we find them here.
Not sure what you’re dealing with? Call (360) 206-3293 for a free estimate over the phone, or browse the full Pest Library.
