This morning I put some chlordane (I have an old bottle - I think it is banned) on cotton balls and stuffed the three holes I found. All day long the bees were buzzing around trying to figure out what happened to their nests.
It was a hot day so we took out our canoe. There is a right-of-way to the Annisquam River where we keep it - it is one house down and across the road. It was a few minutes past high tide so we were able to paddle around the island that is in the river. This is a tidal river that connects Ipswich Bay to Gloucester Harbor. At high tide the water is 9-12 feet over the low tide mark here! As usual, even though we've done this for 26 years or so, the route through the reeds was not remembered very well. I chose wrong so we had to port over a small patch of reed / humocks and rsc did dip is leg into mud on the way. Coming back to the house after we we had a strong wind and the tide to fight so it was a fair bit of work.
While bringing the paddles back up to the house and passing the area of the carpenter bees nests I saw one and tried to kill one with the paddle but didn't succeed. (See, these two topics are related.)
Later when I went back to paint I saw the two bees sitting on the wood under the porch and killed them both with a piece of newspaper. I hope there were only two of them; they do pair up.