Powderpost beetles in hardwood beams
Is there any way to get rid of powderpost beetles riddling oak beams with holes? November 7, 2001
Question
I thought that the powder post beetle would perish under dry conditions. I've had my beams stickered and under cover for up to a year but have active beetles (I see the sawdust under the affected wood). I note in the archives the suggestion that the wood be kiln dried at 130 degrees for 24 hours. Is this correct? Will I be successful with 6x6s? The beams are meant to go into a new house and I sure don't want live powder post beetles inside. Is there an alternative solution? These holes were not there when I first worked the wood.
Forum Responses
If the beams are softwood (pine), then it is not lyctid powderpost beetles. Otherwise, many insects would enjoy wood at 25% to 15% MC (which is what your beams would be stored outside under a tarp). The lyctid powderpost beetle likes wood as low as 8% MC (about 45% RH).
Gene Wengert, forum technical advisor
From the original questioner:
My beams are all hardwood. What do I do about the critter, whatever it is, that makes 1/16", holes from which sawdust comes?
I would try brushing on a wood preservative to stop the bugs.
Wood preservatives will not work on existing beams as the insects are inside the wood and the preservative only makes a poisoned outside layer, which the insects must eat before they are killed.
You need to have the insect identified and then will probably have to have them fumigated by a professional exterminator.
Gene Wengert, forum technical advisor
From contributor M:
If you do not have a lot of wood to process, you can try injecting turpentine into the hole with a syringe and needle from a farm supply store.
I had powder post beetles in some beams I cut and I wrapped them in black plastic and laid them in the sun in June for 3 days. The temperature outside was 95 and inside the plastic on the shady side was 145. The beams were very warm to the touch. I coated the beams with a heavy dose of Durasban (spelling?) and re-stickered under tin. Have not seen any new powder under them. They were 6x6x18' white oak and I did not want to move them much.
From the original questioner:
I'm trying the wrap in black poly with one short beam; if you were successful after just 3 days, I guess I had better unwrap mine as it's been there for 6 weeks. If earlier comments are correct, it sounds like Dursban won't have much effect so your success had to be the heat.
From contributor M:
We are getting fewer hours of sunlight than in July. You might want to increase the heat potential by:
1. Wrapping the clear plastic around the black material leaving an air space (greenhouse effect).
2: Using a dull black material around the beam, as shiny black plastic will reflect some of the heat/light away.
3: Placing an electric heater inside, under the beam (but not too close!).
From the original questioner:
It turns out that poison injection is not practical because, as I rework the beams, I'm finding lots of little holes, almost always in the red oak. I'm going to have to try the plastic and sun route. I will leave them out for a fair length of time.
From contributor M:
If you've got that many bug holes it is probably black oak, which is a variety of red oak that bugs just love.
Heat (over 130 F for 24 hours or more is required) is very effective in killing the eggs and the insects. After the insects lay their eggs, it may be up to two years before they hatch, so be careful about an inspection that shows no further damage--there can be more in a while.
Gene Wengert, forum technical advisor
From the original questioner:
As an aside, freezing kills bugs, tropical ones at least. We lived in Thailand for 4 years, where I acquired a lot of buggy baskets. Our house had a walk-in unused freezer where I placed all newly acquired baskets. I saw no signs of the critters after I pulled the baskets out. The Thais traditionally put their baskets in a smokehouse to take care of this problem.
