These ants lack the concave depression on the top of their heads which Formica exsectoides and all other F. exsecta group members have, therefore ruling out the possibility of them. Formica obscuriventris are also known to create mounds like this, and they are present in Maryland.
I'm looking at the ant in the center right of the last pic. There's another ant down diagonally to the right of that one that you can see fairly clearly. To me, they both appear to have concave depressions on the top of their heads.
Oh, I didn't see that. When i posted the answer of F. obscuriventris, I was on my phone. Looking at it from the big screen, I agree, these ants do have the concave depression, therefore concluding that they are actually Formica exsectoides.
Good catch, next time I'll remember to look at photos on my computer.
Thanks. There's no doubt that you know your ants better than I do. In fact, I look forward to it when you ID mine because the odds are good that you're correct. I got lucky on this one - even a blind dog finds a bone once in a while.
Edited by Jamiesname, May 3 2019 - 6:04 PM.
