This one species is something of the black sheep of the genus. It's the only one found outside the south west region of the US. All the other species in the genus are restricted to Texas, Arizona, California, and that general area down there; certainly not as far north as this species.

Added: As far as the threatened plant goes. I wouldn't take vengeance out on the ants. A somewhat even more threatened butterfly species or two use Lupinus perennis as a host plant. Specifically they feed on the flowers and seed pods. Once grown up the caterpillar has to over winter or spend a season inside a host ant nest. I would be interesting to know if Trachymyrmex species were a suitable host, especially since their diet is somewhat different than the average ant species.

Thank you for the ID and the info. I wouldn't harm one tubercle on their tiny little heads. We are also helping to monitor for the rare butterfly that uses lupines in our area, the frosted elfin (Callophrys irus). I'd love to know more about the caterpillars that overwinter in the ant nests, do you know which species are involved, or where I might get more info? I googled for about an hour to no avail...

Hi Sara, do you remember the exact location of where you found these ants? I also live in Odenton and an antkeeper and would love to find them. Thanks