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Are the Holes Old or New Powderpost Beetle Damage?

By Chris Williams on April 13, 2015.

Illustration of a Powder Post Beetle“Last year we had a powderpost beetle infestation in our unfinished basement that was treated by a pest control company. I was just down there and saw sawdust on the floor. I see some holes in the beams, too, but can’t really tell if they are the holes from before. How do we know if the beetles are still there?” L. C., Boston, MA

Fortunately, spring is a good time to find out whether your powderpost beetle infestation is still active. The adult beetles emerge from the wood in the spring, leaving behind tiny round, exit holes. The little dark beetles are rarely seen but they are attracted to windows and lights.

Signs of Powder Post Beetles

The exterminator who treated your home should have cleaned up the sawdust (beetle “frass”). Frass is the digested wood that has passed through the beetle larvae. It’s made up of tiny wood pellets, but looks sort of like sawdust. Ideally, the exterminator should also have marked the existing exit holes in the wood. That way you would know that any new holes mean beetles are still present.

Fresh Frass Looks Different

The appearance of new frass may mean active beetles, but it also could be last year’s frass that has since drifted out of old holes as a result of vibrations in the house. A technician with a well-trained eye can sometimes tell by looking whether the frass is new or old. Fresh frass is powdery and lighter in color, like newly sawn wood. Older frass will be yellowed, cakey, and darker. Likewise, new exit holes will have lighter, fresher-looking edges.

You could try sweeping up the frass yourself and checking for new frass to appear. You can also mark the exit holes that are present (or take a photo) and keep an eye out for new holes to appear. The adult beetles emerge over such a narrow period of time, however, that if they have already emerged you may not see any more activity until next year. Unfortunately, adult emergence is often the only visible sign of a powderpost beetle infestation, unless you break open the infested wood to see the damage.

You might want to contact the company that did the treatment to see whether they offer a followup inspection or what their warranty terms are. Or, give us a call at Colonial Pest. Our technicians can inspect for powderpost beetles and let you know whether you still have a problem, or whether what you’re worried about is old evidence from a problem that has been resolved.

Photo credit: Internet Archive Book Images / Foter / No known copyright restrictions

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