I recently (21 July 2011) caught queens after their mating flight. Unfortunately I have no idea which species these ants are. I caught them in the Uppland area of Sweden. They are black, and some have white/yellow stripes on top parts of their abdomens. They are about 1.5 cm in length. They look like the Lasius niger queen that I have but slightly larger (and with the stripes where the segments meet).
My question is therefore (rather than just getting an idea of which species this is, although this would be appreciated ), how do you go about identifying which species you have?
R