I was working with a good friend and garden client, Ann, yesterday. We were digging out a big space in her backyard to make way for a new little pond she wants to put in. During our digging and chatting she said carpenter bees had moved into her trellis system. She's waiting for the painter to come and help her paint, which will help keep them from feasting on the wood. But in the meantime, she said she feels odd about killing the loud bees. They do pollinate, and she is very worried about killing any pollinators. What do you think, she asked me.
This is the kind of question I love, partly because I think it is great people are pausing now and not just automatically reaching for insect killing sprays at the first sign of any insect. We are slowly learning to respect and understand the species around us, even those that might sting.
I don't know much about carpenter bees. My dad says he used to catch them when he was a kid and tie dental floss to their legs and fly them like a kite. This is odd, but also evidence that these bees rarely sting. In fact, I think the males are physically unable to sting. (This is also a bit of insight into how the mind of a future biologist works: he learned which bees stung at a young age in order to impress the other kids in his class, apparently.)
Still, all that said I would opt to kill them if they moved into my outdoor woodwork. They will eat at quite a voracious rate. Searching around on google you find stories of people who had to replace entire decks which were tunneled to smithereens by these bees. I don't think the pollination services which they can provide do not outweigh the damage they can do.
When I see these bees at the park or playground, I love listening to my kids tell other kids: don't worry, they don't want to hurt you. They just want to eat the jungle gym. I just hope no one has any dental floss on hand at those moments.