Drilling is all they’re doing. That being said, in my experience. But don’t forget that carpenter bees aren’t eating any of the wood.
Chip zien into the woods
1638 plantation woods way
Pottery barn wooden bowl
Wood Boring Insects EcoGuard Pest Control Inc
But remember, carpenter bees aren’t eating the wood.
I’ve seen plenty of nests located in pressure treated lumber so whatever is being injected does not seem to slow them down or kill them.
They’re only drilling through it.