Argentine ant nest in a wall. This seems most likely. The size just isn't right for carpenter ants. And I might be wrong, but I'm pretty sure red carpenter ants are winged. (like this) Then there are these. read more
While other ant species have seasonal swarming flights, these ants do not form new nests through mating swarms. Instead, they mate inside the nest. A single Argentine ant colony will have several queens, each of them capable of laying as many as 60 eggs per day. read more