Paul,
Any idea what they are? Termites? Beetles? etc? Did they come from holes in the wood or are they coming from a bark inclusion? To identify them you will probably need to know the species of tree. Many beetles feed on just one or a narrow range of woods.
I live in Hawaii, which we all know is incredibly similar in climate and flora and fauna to Pennsylvania. But....for what it is worth, the bugs we deal with here are termites, Formosan mostly, and powder post beetles and powder post termites. Both these critters like dry wood, with 12% moisture levels roughly. We also have a tree termite that wants wetter wood, but it is usually not a problem for turning since our stocks dry out fairly quickly. I think you deal mostly with Eastern Subteranean Termites, and a variety of wood boring beetles depending on the wood species. It is usually the larva of a beetle that is doing the chewing, not the adults.
For the termites and beetles here you usually use a commercial product called Timbor to soak the wood. I don't know how it affects the turning and finishing characteristics though. At least on the commercial lumber I buy that has been soaked in Timbor it leaves a white powder on the surface as it dries. I suspect the powder would keep recurring over time as moisture leaves the wood. And it seems to take a long time to dry. Although it works well I have come to despise it everytime I pick up a soaked 5/8 sheet of plywood. Stuff was heavy enough dry. It is miserable when soaked through with Timbor.
Ortho also makes a product called Ortho-klor for termites and other boring insects, and I think they have another one for boring beetles, but I can't hink of the name off the top of my head. I dislike using these chemicals though, and would be particularly leary of them for anything that will be handled much by the customer, in spite of Ortho's claims to the contrary. No offense to Ortho, I'm just suspicious I guess!
Some of our turners use a product called WoodTurners Choice from a company called CedarShield at Cedarcide.com Originally they used it as a wood stabilizer but they found that it kills powderpost beetles and termites and soaks throughout the wood quickly and does not affect the finishing and turning. Additionally they use it to reduce the drying time of bowl blanks in woods like Koa from the normal 6 months to a year down to 2 weeks (3 days for other woods) The folks who use it swear by it. Supposed to be non toxic. The company has offered to send samples before so you if you were interested you might contact them about that. I use it and like it.
I am afraid I can't address the microwaving issue. Seems like it would work, but it might take a fairly long exposure to get em! DNA may not bother them that much if it doesn't sink in deeply or have a long enough contact with them. If they are boring insects their burrows can be pretty convoluted and also may be partitioned, preventing the DNA from flowing throughout the cavities. Any larvae in the wood may also have a different level of susceptibility to DNA than the adults as well. And of course, you are likely to have larvae hatching out at various times which doesn't help your control efforts.
Hope this helps you a little!
Dave