Pressure treated wood - attracts bees?
One thing I've noticed about the carpenter bees, since they've changed the pressure-treated wood and taken out the arsenic (it was CCA, now its ACQ) they'll attack it much more readily. I've got a fence and a pergola I built out of the old, bad-but-good stuff with the arsenic (cough cough) and they won't touch it. And I've also built an arbor and a tiki bar out of the new stuff without the arcenic and they're tearing it up.
Now I'm a liive and let live type of guy, so at first I left them alone, because its only a small hole that they make and it only seems about a couple of inchdes deep. And they don;t really eat the wood they only use it to make a nest. But then I startied researching them and found out that they bore the entry hole peppenicular to the grain, and then go parallel with the grain with a hole that can be 2 or 3 feet long, with side tunnels branching off for the eggs! And on top of that, they have a homing instinct. So the baby bees that leave the nest in your wood will return to make even more nests and have even more babies. So every year you'll have more and more! So we're talking major strucutral damage here.
So now I try to take them out. I read that WD-40 will kill them, and I've tried it and it really works! WHen you see a bee go in the hole just stick the red tube in as far as you can and give a squirt. In a minute or two the bee will come staggering out, drop to the ground, and die. Also its kind of fun to pluck them out of the air while hovering with a BB gun.
I was going to paint or stain my new stuff for next year because I read they didn't like that. But yours is already stained and you're still having the problem? I might have to try something like that beeb-b-gone stuff.