Once again, these ants are found in firewood.
At first glance the workers look somewhat like Camponotus pennsylvanicus carpenter ant workers. This worker is in the 6.5-7 mm range.
The surprise comes when an alate comes crawling out of a tunnel. At this scale you probably still can't see the difference.
That alate is much smaller than an alate of of a Camponotus pennsylvanicus.
Looking closely at a front on view of a worker's head, you find that they lack hairs on the genae and have few on the clypeus. These are Camponotus nearcticus workers.
I was a bit surprised, because in the area I was collecting I had typically encountered C. nearcticus with a brown-red mesosoma, like this one at BugGuide. Just goes to show, once again, that color is not a useful guide to identification in ants.
According to Hansen, this species is spread throughout the eastern United States and across the northern U.S and southern Canada all the way to the West Coast. They are even found in certain parts of Arizona, although not in the low desert.
The alates are apparently reared in the fall and overwinter in the nest, as with other carpenter ants. I did not find any larvae or other immatures.
Their biology seems to be similar to that of other carpenter ants, but they have not been studied extensively.
Have you ever encountered Camponotus nearcticus?