Pavement Ant War, Close Up

2023 May 14

The Pavement Ants (Tetramorium immigrans)[1] that live beside our walkway to the barn were at it again on May 10, 2023. They were battling it out over a patch about a foot and a half long and maybe six inches wide. And given that they are pretty tiny ants, this meant there were thousands of them. While I have had pictures of a pavement ant battle previously, I have upgraded my lens in the meantime, so we can see them better this time.

The majority of the ants were either wandering around looking for trouble, or engaged one-on-one with other ants. Pavement ants don’t appear to have stingers or chemical sprays for combat, so this mostly amounted to locking jaws with one another and wrestling.

When the numbers are evenly matched, not much happens beyond this. But, if one side gets numerical superiority, then the ant that is outnumbered is in big trouble. If her jaws are busy with the first opponent, then there isn’t a lot she can do if a second one starts chewing off her legs.

And, of course, if additional opponents show up, then it is all over for her.

This didn’t actually seem to happen all that often, though. After tussling for maybe an hour or so, both sides apparently decided they had adequately defined/defended their territory, and retreated back to their nests. There were no bodies left behind, I presume that any ants that were killed were dragged home by the opposing side and eaten.

An interesting thing about these wars is that they don’t go on all the time. A pair of nests will duke it out maybe once or twice a year, and the rest of the time will just stake out their territories and ignore one another. So while a battle may be a significant effort for them, they do it rarely enough that they don’t exhaust themselves completely.

[1] When I posted the previous battle pictures in 2015, they were still called “Tetramorium species-E”. At the time, it had only recently been discovered that, while they had in fact been accidentally imported from Europe, genetic studies showed that they were not the Tetramorium_caespitum that everyone thought they were. It took a while to give them a new species name, and so now they are Tetramorium_immigrans.[2] It was kind of a weird situation where the species had never been recognized as distinct in its native range, and it wasn’t until it invaded somewhere else that it was seen for what it was.

[2] I hadn’t seen AntWiki until just today. It has a lot of information that BugGuide doesn’t have, provided that what you want to know about is ants.

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