The smaller form (following picture) is the species' male. I wrote "cf" between Genus and species name to express that this species is, if not C. nearcticus itself, at least a very closely related one, from the same group (subgenus Myrmentoma).
Among Carpenter Ants from temperate climates, it is usual for the sexuals to overwinter as young adults in their natal nest, swarming only the following spring (from late April to early June).
That this one female lacks apical segments on her left antenna suggests that some fighting has occured with a neighbour society, or any other insect foe. This too is a peculiar habit of this genus: youg females tend to behave like their big worker sisters, and do take part at the nest's defense.