I am still new to the wood burning community so i don't know for sure what is in the wood. However, i am pretty sure i can tell you what they are not. i had to replace an entire sill beam in our 100+ year old farm house that was eaten by powder post beetles. these guy are REALLY small. the holes they bore are about the size of the period at the end of this sentence. So if what you are seeing in your wood is larger than that, then i don't think they are powder post beetles.