Carpenter bees are very hard to eradicate. I had my deck sprayed by a pest control company with Permethrin. If any of you guys are from the east, this is the best tick repellent you can buy if used exactly as directed. Its also the "green can of death" stuff for any of my fellow Army guys!!
Anyway, it worked for 2 years. They are back this year and I'm about to call them back out to spray again. The only true way to get rid of them long term is to plug every hole with a 5/16" dow rod slice. You can Google to find out if the 5/16" is correct....but they bore such a perfect hole that every one is exactly the same diameter. Problem with that is, you have to plug every hole. And in about 4-6 years they could still come back. I've read and read about how to get rid of them, and never found a good answer. Good luck, but I'd have someone spray for you. Being in California though, permethrin may not be an option.
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