Formica gynocrates

A few weeks ago I mentioned my discovery, just down the road from my house, of a Formica field ant species I’d never seen before: Formica vinculans. This active little ant is a prairie specialist, and I was surprised to find a healthy population in downtown Urbana. We’ve lived in our present house for several years, and these had somehow escaped my notice the whole time.

I should have suspected these little ants would host parasitic ants I’d also never seen. And so they do!

Last week I chanced across a raid by the social parasite Formica gynocrates, spilling across the sidewalk with their mandibles full of F. vinculans pupae. Formica gynocrates are one of many so-called “slave-raiding” ants that benefit from the labor of ants taken as immatures from the nests of other species. I didn’t have my camera with me for the raid, but I returned later to capture a few photographs at the parasites’ nest.

Formica vinculans (left) with its Formica gynocrates social parasite.

A remarkable aspect of ant taxonomy, even in well-studied faunas like our midwestern one, is that many species are still essentially unknown. Formica gynocrates was not formally described until 1985.

Formica gynocrates

Formica gynocrates with Formica vinculans

Formica gynocrates

photo details:
Canon MP-E 65mm 1-5x macro lens on a Canon EOS 7D
ISO 250, f/13, 1/250 sec
diffused MT-24EX twin flash

thanks to James Trager for helping confirm the ID