rough sawn English Sycamore with powderpost beetles

1) I have heavily treated a bunch of roughsawn English Sycamore boards with BoraCare after noticing several small pin holes appearing with fine saw dust, etc.  It has been a week since treating and today I noticed several more holes with saw dust in the boards.  Is this normal?

2) I make musical instruments and have already finished a bunch of wood to the correct dimensions etc.  Is there a way to determine if these boards have eggs inside them?  Would freezing the boards help destroy any eggs that could be in the wood?  The wood is no more than 1/4″ thick.

If you read our POWDERPOST BEETLE CONTROL ARTICLE, you’ll notice there is a picture below the 5th paragraph showing exit holes on a hardwood. In fact the firth paragraph explains in detail what it is you’re seeing on your English Sycamore boards; it’s actually adults boring out exiting the wood after completing their 3rd stage (pupae stage) of development. As our article explains, when you treat there will be a certain population of these pupae still developing in the wood and at some point they’ll hatch out. The BORACARE you sprayed won’t affect them since they’re not eating anything. So this means that when they hatch out of their cocoons, they’ll drill out of the wood to the open air as they emerge so to will a fine powder (hence their name “powderpost beetles”). So in summary, what you’re seeing is to be expected; only after all the pupae hatch will the cycle run it’s course and be done.

The good news is your treatment will at some point (if not already) affect any larvae present that might be feeding. As you know, the Boracare penetrates through and through the wood and once the larvae eat some wood treated with Boracare they’ll die. This is actually the key to breaking the cycle of this destructive beetle. You didn’t mention how thick the wood is in your section “1)” but if it’s 1/4″ thick like the wood in section “2)”, the Boracare would have penetrated through and through by now. If that’s happened, no more chewing or damage is happening as any larvae present will be dead or just about to die. Unfortunately there is nothing that can be done for the unhatched pupae other than waiting for them to “run out” and all of them to emerge.

Lastly, there is no way to determine if any wood has eggs. And even if you could tell there is no way to kill them all. Only after the egg hatches and the larvae attempt to feed on the treated wood will they die. When feeding on the lumber you sprayed they’ll ingest the Boracare and quickly die off. I know this doesn’t offer much in the way of preserving your finished wood that sounds close to ready to become a musical instrument. But I don’t think there is anything you can do short of waiting. As I see it, a good idea would be to treat all the lumber you want to use and then store it for a decent amount of time to make sure there are no pupae waiting to come out. As our article explains, some beetles can lie feeding for many years. Should you wait this long before using the wood? I don’t think so. But I do believe 6 months is a reasonable amount of time to wait and I know some people who will wait over a year before using any lumber they treat just to be sure. Even that’s not a guarantee something will drill out but in most cases it’s long enough. Hopefully this gives you some kind of  guage for how long you too should wait before final processing. I’m guessing that just one exit hole would ruin your piece so there is really no room for error in the work you do. If that’s the case, waiting longer seems like it would be the smart approach.

For your benefit, here are direct links to the information and products listed above.

Powderpost Beetle Article:



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