I would start out by contacting my local Agriculture Agent and see what he says. If he can't help, I'd try my local pest control and see what they say - but they might well want you to pay for their services, I don't know.
And, you can always search on-line and see what you come up with. I recall someone having a similar problem some years ago, but don't recall now what the solution was. Borax seems to pop into my mind. In another case an individual took apart a small log cabin and reassembled it inside their home. With live bugs in it, says they can be heard munching when it's real quiet. But the concenses was, after consulting an expert, that they couldn't breed in there, and would eventually all die out, and no structural harm done. So they were left alone.