Sunday, July 11, 2010

Not Carpenter Ants

As I was walking through the woods, I came upon a column of rushing red and black ants. Large red and black ants usually mean Mound Builders, so I stopped to see what they were up to. The first thing I saw was a worker carrying a cocoon, so I thought I must be witnessing the move of a colony.

Then I saw an ant carrying something dark in color. This worker was carrying a black ant. Instead of a move, this must be the result of a raid and the ants are carrying their booty back to their nest. I used a glass vial to capture a worker carrying a dead ant, so I could identify the prey. Oops, as soon as I lifted the vial, the two ants broke apart and started running around the vial. No one dead here. After a few seconds, the black ant stroked antennae with the red/black and presented itself to be picked up. Now unless this was a Shmoo ant, that kind of behavior was out of character for the prey.

I decided to follow the column to find the nest being raided. I found the general location, but the specific site was in a thick clump of grass and it couldn’t be seen. I then began tracking in the other direction to find the home nest.

After traveling 180 feet, I came upon a hole in the ground into which cocoons were being carried, but it was not the typical nest of the Mound Builder. Now I again became confused. Here were multicolored and black ants living together in the same nest. Could this be some sort of slave ant relationship?

It seemed that both color groups could work lift-and-carry duty. The more I watched, the more obvious it became that the red and black individuals were not Mound Builders. The shine and shape of the gaster (that inflated rear end of the ant) was pretty much the same on all individuals. Could these be two different color phases of the same species?

A little bit of reading in Gary Coovert’s “Ants of Ohio” book leads me to believe that these are Camponotus nearcticus, a species of Carpenter Ant common in Ohio. The magnification equipment I have available isn’t quite sophisticated enough to allow me to check the condition of cheek hairs on ants, but based on other characteristics and the description of possible color morphs of this and similar species, I’m pretty sure of the identification. At least until someone points out how terribly wrong I am.

5-28-2011 NOTE: I guess I should have read Gary coovert's book more than a little bit. It's been pointed out to me that this is one of the species of ants that raid other species' colonies and capture workers for adoption into their own colony. It now looks like this is most likely Formica subintegra. The text description of a colony of Formica subintegra moving to a new location exactly fits what I was witnessing. Funny how sure you can be about something until someone shows you that you are wrong. I appreciate having this misidentification corrected for me. I'm always interested in learning new things and now I know to be watchful of raider ants.

It was an exciting encounter, despite the fact that I had to change my mind several times about what was going on. Ants are always interesting creatures to observe.

Here’s the route the ants followed during their move, or whatever their trip was for. They traveled 180 feet from the farthest sunny opening near the top center of the picture to the base of that nearest tree. That’s quite a trip for something that small, especially when you’re carrying one of your buddies in your mouth.


  1. Pretty amazing detective work! Reminds me of that song - just what makes that little old ant, think he can move a rubber tree plant...ha, ha, I'll be singing that in my head all day now! ~karen

  2. I've always found ants to be interested, unless they are carrying bread crumbs across my livingroom. One day I watched three of them carrying a dead dragonfly to their lair, then race around in a quandry trying to figure out how to get it in. A gazillion of them came to the rescue and helped break it down. It's amazing how they work together to accomplish the most major of tasks.

  3. Wow! Reminds me a little of when I was in Australia and would entertain myself during boring stretches of waiting for the birds I was observing to return to their nest by watching the columns of ants marching back and forth - occasionally I would gently scratch a stick across one of the highways and watch them scurry around trying to rebuild the scent trail. Sadly I have no idea what and species it was that I found so entertaining.

  4. I really don't know that much about ants, perhaps I should know more, but I admire your macro photography.

    Thanks to you for visiting my birds blog.

  5. Karen - That song has run through my mind about a thousand times today.

    Renee - I've always enjoyed watching ants, even when they're busy cleaning bits of food from the kitchen counter.

    Rebecca - When I was in college, I did a study of ant species interactions at food sources. I spent weeks sitting in the field watching how ants sorted out which colony had first rights to the food. I never tired of it.

    Hi, Abe. If everyone knew everything, people wouldn't have much use for one another.

  6. I feel a little silly commenting on something so old, but I've been looking for pictures of Camponotus nearcticus and what you have here are Formica; possibly Formica aserva, with Formica (fusca) sp. slaves. As a budding naturalist, I just felt I should point this out. :)

  7. Thanks, A. It's never too late to correct an error. I rechecked and it looks like these are probably Formica subintegra. I've made a note in the post to show this.