Ant identification: February 2013 Archives



I'm sure you get a lot of questions phrased like my subject heading. But I'm stumped here! I've linked to two pictures I took in the woods in Atlanta, GA.

http://www.flickr.com/photos/65837114@N00/7578847944/

http://www.flickr.com/photos/65837114@N00/7578844086/

From the far shot, it looks like the ants are "herding" the insects into a big clump. in the closer shot, you can see that some ants have actually dived into the fray.

Were these ants really herding the other insects or had the insects been swarming beforehand and the ants are just there to pick some off as food?

Also, I can't seem to identify the insects in the pictures that the ants are interacting with. They look like some kind of insect in the nymph stage.

If it matters, the tree in the picture is a beech, I think.

Thanks for your help! I'm so glad I found this blog!


-Becky

Dear Becky,

Thanks for the great pictures! Yes! Many ant species have facultative mutualisms with aphids (seen here) and other herbivorous insects. The ants guard the aphids from predators, and, in exchange, the aphids essentially poop sugar water into the ants mouths. This "honeydew" as it is euphemistically called, has to be voided from the aphids, because they have to go through a lot of plant sap to get enough minerals and amino acids. To the ants, it's gatorade.

The ants are most likely the common carpenter ant, Camponotus pennsylvanicus. I don't know much about aphids, but those are really big, and they seem to be on the bark of a deciduous tree, so they might be the giant bark aphids, Longistigma caryae. There're probably some other big aphids out there, but this seems to be a pretty widespread, conspicuous species, and they have been reported to associate with C. pennsylvanicus elsewhere in the Southeastern United States.

There have been a few posts about this relationship in other blogs (such as here and here ) and there's a rich scientific literature of ant-aphid mutualisms you should check out if you'd like to know more! There are also some pretty great photos that have been posted by others!

Thanks again for your great pictures!
best,
Jesse

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