I live in a log house and every spring, carpenter bees make holes in the logs. What can I do to get rid of them?

Look at Do It Yourself Pest Control Products I used their recommended products to get rid of some bees I had.

Carpenter Bees make those holes to lay eggs in. The larvae that hatch eat their way out, doing further damage to the wood. Unless you're prepared to spend a lot of time getting insecticide into each hole(which can be 14 inches long) to kill off the larvae, I'd recommend hiring it out to a pro. After the bees are out, an oil based sealant or a polyurethane will help keep them away next year. Yes, that's a lot of money, or an entire summer's project.