1.   A. They could be powder post beetles or old house borers.

2.   A. They may be powder post beetles, which can get into wood and leave tiny, telltale holes along with a powdery sawdust after they do their work.

3.   I think they are powder post beetles or borers, of which there are many kinds, some of which can reinfest wood, others cannot.

4.   Then again they could be powder post beetles or the old house borer, both of which can do a real job on wood.

5.   Usually insects such as powder post beetles and the old house borer actually bore into the wood, creating telltale holes and depositing the sawdust in little piles.

6.   Yep, that is what they are called, and there are many kinds of each, although powder post beetles generally attack only hardwoods.