Shot 08/13/2012 @ 3:45 PM.
I've been checking up on this Formica colony in Madison, ME every summer for the past three years, and this time around I noticed some of its workers frantically burrowing into the earth, beneath a clump of grass, a little ways from a satellite nest. After I set up my camera, I found out why. I interpret this as a food-gathering raid, since cryptic Lasius don't offer much in terms of competition or viable host workers to this obligate slave-raiding species. After about a dozen of the Lasius workers were piled up outside the excavation, the attackers pulled back and hauled the haul back to one of their nests.
This Formica subintegra colony has thousands of raiding workers, with likely up to nine times as many "slaves". Truly, there were no other species of Formica in the immediate area. Their nest composes of 3 sites, about 20 meters apart from each other, often with a constant stream of raiders and host workers between them.
It's interesting to see the raiders participate in what is essentially foraging. Perhaps they make some significant contribution to food gathering in what they take from other ants.