Temnothorax Crassispinus
I believe this is the ant species "Temnothorax crassispinus" although looking around, many of the Temnothorax species look very similar. These ants are absolutely tiny. To give an idea of scale - the hole you can see is just wide enough to fit a standard sized pencil in. Ants of this species rarely have colonies bigger than 100. Apparently they are quite friendly and get on well with other species of ants...
Temnothorax crassispinus is an ant in the Temnothorax genus. The workers of Temnothorax species are generally small. Colonies are typically monogynous, although facultative polygyny has been documented in several species. Colony populations are usually quite small, often with less than 100 workers. However, several studies have found colonies of some species to be widely dispersed with several to many satellite nests. Many species are arboreal, living within hollow stems, old beetle or termite galleries,.. more