Biodiversity of ants in Hartford community gardens, Conservation Training Partnership project by David Cappaert and Lucia Volin: PDF
Species collected below. The parenthetical number is the number of sites (of 12) where the ant was detected. A few species were not seen in the study sites, but were observed in Keney Park.
Myrmica americana (2)
There are 20 or so Myrmica species in our area. There are sometimes subtle differences that distinguish the species. In some cases, we don't even know the species - some are just provisional, until further study demonstrates who's who.
For this one, the ID is based on the spoon-shaped lamella at antennal bend of the scape.
Lasius claviger (2)
Tiny, lemony-smelling ant common around Hartford, typically under rocks. It is a temporary social parasite - a queen invades the colony of another species (e.g., Lasius neoniger), and kills the host queen. Eventually the colony rears the new queen's brood, and the colony becomes a pure L. claviger colony.
Crematogaster cerasi (1)
Unmistakeable, with an "upside down" heart-shaped gaster.
Camponotus novaeboracensis (0)
A bi-colored species that nests in rotted wood.
From Ant Wiki: The pupae of this medium-sized carpenter ant are often parasitized by small Pseudochalcura gibbosa wasps; the larvae of these wasps are taken back to the nest by the ants as a food source for the developing brood. But the eaten become the eaters, as some of the wasp larvae develop and then devour the ants. (Ellison et al. 2012)
Camponotus chromaiodes (0)
Another bi-colored species. Note that (unlike C. novaeboracensis) the first gastral segment is red, and that the gaster is very pubescent.
Myrmica rubra (6)
The European fire ant is invasive, to both the Northeast and Northwest US. One study in British Columbia demonstrated that M. rubra accounted for 99.99% of the ants in infested areas.
M. rubra supposedly has a painful sting. I haven't experienced this, but look forward to an opportunity to test it.
Tetramorium immigrans (10)
Another European invasive common in urban environments--the common name is pavement ant. They are sometimes seen indoors in large aggregations following pheremone trails to food sources.
Note: the photo above made with a macro lens. The lower image is the same specimen made with microscope, and a focus-stacking program.
Solenopsis molesta (10)
Probably the smallest ant in Hartford, at ~1 mm. S. molesta, the thief ant, can occur near or within the nests of many other species (Lasius, Formica, Camponotus), from which it steals food.
Brachymyrmex depilis (2)
Poor image ... too tiny. But 9 segmented antennae diagnostic.