Doc Green
Here in central NC I have a big problem with wood borers. An adult is a worm about 3/4" long and 1/8" diameter with an over-sized head. Don't know if you have such a thing where you are.

For a roughed-out bowl blank with holes that indicate a borer might be present, I place the blank on a clean surface and wait for the dust to appear. The dust points me to the hole (1/8 or 3/16" diameter) that has an active worm. I then use a medicine dropper to inject a good squirt of lacquer thinner into the hole, then replace the blank on the clean surface. I keep doing this until I get no more dust.

Sometimes the critter will back out of the hole. Apparently they don't have a taste for lacquer thinner.

I've tried microwaving the blanks, but it didn't work. Obviously I didn't get the blank hot enough to kill them for fear of destroying the blank. I built a vacuum chamber, and pumped it down to 20" Hg with a blank inside, and held the vacuum for about 5 minutes. Didn't work either.

What does work is a woodstove. I've never seen a borer come crawling back out once I threw the blank inside. This winter, I've burned over 100 blanks of ash, not roughed out but carefully sawed out. sealed, and stacked, that the borers have destroyed. Good luck. ~Doc