sawdust on oak hardwood flooring


I recently installed a new oak hardwood floor. It was raw wood which I stained (oil base) and finished with polyurethane. Shortly after, signs of powder post beetles were evident. Though it took me a week to figure out what the heck the little piles of sawdust were all about, I am now adamant to get rid of these buggers. I certainly do not want to refinish these floors, so I am curious about the Jecta Gel. Can I apply it in the pinhead size exit holes? Is the applicator that small?

Also, I’ve read that these adult beetles are looking to mate and then lay more eggs. If my floor is now finished with polyurethane would it be safe to say they probably would only go back into the holes they made? Would they create a new hole in finished wood?

And lastly does stain and polyurethane kill them? I had a thought that perhaps the stain and poly could possibly be driving the ones that weren’t killed out and that these holes (there have been about 7 total in two weeks) would be the last I see of them. What do you think?



As explained in our POWDER POST BEETLE CONTROL ARTICLE, hardwood floors can be tough to treat for powder post beetles. The activity you see right now are undoubtedly adults emerging as they complete their life cycle. Exit holes might present the most direct way to treat the wood without rigorous preparation and for now, I’d say you should use these exit holes to your advantage. As our article details, JECTA GEL or DFORCE AEROSOL would be viable options for any direct treatments including exit holes. The tip of the Dforce injecting nozzle is ideally suited for exit hole treatment; Jecta Gel has a nozzle/tip which is too wide to get the gel into most exit holes without waste and some mess. I like to drill exit holes larger prior to treating which enables me to get more gel into the hole for better coverage. You can still attempt to treat without drilling the flooring; expect some mess but if you are patient and willing to “push” in the gel with a spatula or some other tool it can be done. However, drilling larger, oversized holes is definitely a more effective approach.

If the floor is tight and the urethane “blankets” the entire area, it’s most likely the only good spot for adults to lay eggs would be in previously made exit holes. However, in all the traditional oak hardwood flooring I’ve seen over the years, there are always gaps and spaces which powder post beetles can utilize if located by foraging adults. By design, traditional hardwood flooring will contract and expand with the season. In winter months, it typically contracts exposing subtle seams and spaces. These may be hard to see but to small insects like Powder Post Beetles, they present prime nest locations and are easy to find. I’d be surprised if there aren’t any gaps in your flooring so be sure to inspect it carefully. If found, treat with either Dforce or Jecta Gel to eliminate them as prime nest locations.

Stain and urethane will kill most any insect when it’s wet and being applied. Once dry, it won’t have much effect on any insect pest – especially powder post beetles. So to answer your question; yes, either will kill the larvae stage of powder post beetles easily when being applied. And if you directly apply either to adults, you’d kill them too. But the eggs and pupae are a lot tougher to kill and generally don’t come out in the open. For this reason it’s not likely you’ll be able to have much of an impact on them when using stain or urethane on your flooring. Even Jecta Gel or Dforce won’t kill eggs or pupae; these products mostly effect larvae as they feed and since both provide long term residual in the treated wood, you can effectively protect your flooring when either are used. Stain and urethane loose their killing action once dry and typically don’t penetrate deep when applied so they cannot reach the “heart” of the wood which is where larvae like to live.

In summary, I would at least treat exit holes and any gaps or seams I found in the flooring at this time. The Jecta Gel or Dforce should be used and I would expect any good treatment made now should make further infestation unobtainable. But keep in mind it could take another few months for all the hatching pupae to cycle down. In other words, don’t expect all exit holes to cease being made following the treatment. As our article explains, the pupae are encased and cannot be killed with any liquid, aerosol or gel treatment so only after they hatch and emerge will you be effectively “done” with the local population. And if you’ve prepared any vulnerable wood with either treatment mentioned above, you should be able to stop them from continuing their cycle. If you have further questions or concerns, please give us a call on our toll free 1-800-877-7290.

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