Formica Obscuripes

As a kid, I played with red-headed ants all the time, knowing that they were the most aggressive ants we have around here in western Washington. My friends and I would capture them and put them in a jar with a wasp and watch in fascination as the ants would clasp onto the wasps legs and wings and not let go. The wasp would bite a few of the ants, killing them, but would eventually be taken down and overcome.

The red-headed ants could take on anything - wasps, beetles, roly-polies, worms - it didn't matter. They do this "death grip" thing, where they bite down and don't let go until their prey stops moving.

Today, I learned something else.

Formica Obscuripes uses their acid to signal attack. I captured a couple of them (I'm still at work without my camera) and tossed them into a jar. Within seconds, I could feel moisture on my pointer finger as the captured ants spit on me, and seconds later, there were hundreds of these red-headed ants coming after me, following the movement of my hand as I went to pick them up. And the smell is strong - it smells just like vinegar and tastes like it too.

Anyhow, I've got a jar of about 10 of them that I'll take home and video fighting against some large predator. And if the weather holds up, I'll bring my camera to work with me tomorrow so you can watch a bunch of these red-headed ants charge at me. It's a little scary, really.

Here are a couple of documents I found that outline F. Obscuripes behavior:

Territorial Behavior
Trail Laying Behavior