Q: We have some small holes (smaller than 1/16 inch diameter) in our oak lumber that we have noticed have small amounts of fine sawdust pouring out. I think that our wood is bugged, but the dry kiln people say that their procedures kill all the bugs. Can you identify the problem?
A: There are only two bugs that inhabit kiln-dried lumber: the termite (which has huge holes) and the lyctid powder post beetle. There are many powder post beetles, so we need to identify this one by using the name lyctid. This beetle leaves holes, 1/16-inch or smaller. These are exit holes, meaning that the beetles are leaving the lumber and looking for some more hardwood (not in pines, etc.) to start a new family.
They like the roughness of oak for laying eggs; they do not like smooth maple and any wood with a smooth finish. When they lay their eggs, the larvae hatch, then enter the wood - it may be several years before they exit. Usually we will see the exit holes in the springtime.
Insecticides put on the lumber will not kill these bugs. You can fumigate the lumber or heat the lumber to 130 degrees F or hotter. Lumber leaving a kiln that has been operated at 130 degrees F or hotter is indeed sterilized - no fungi, bugs or eggs. But, exposure of kiln-dried wood to other lumber that has the bugs hatching will likely result in infection of the freshly dried lumber.
If you have some infected lumber with exit holes, first you should promptly (within the next hour) move it away from all other hardwood. Then decide if you will have it commercially fumigated or put into a kiln for a day or two. The problem must be promptly addressed; it does not disappear by itself. The eggs may hatch in a year or two in a product that a customer has already purchased.
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