Ant wars

Boundary disputes settled by all-out warfare.  Sound familiar?

pavement ant war

Ants erupt from the pavement edge in response to intruders from a nearby colony.  

Such eruptions of millions of these pavement ants from their nest happen infrequently, but predictably in the spring, when colonies get too large and need to expand, only to find that they have trespassed on a neighboring colony in their expansion.  Pavement ants are fiercely aggressive, attacking members of another colony with their large mandibles and ripping heads from bodies.

pavement ant war

Members of one colony face off head-to-head against members of another, as you can see from the two by two line-ups in the photo.

Tetramorium caespitum-

My macro lens wasn’t up to the job of zeroing in on these tiny (less than 1/4 inch) critters, but photos by Alex Wild illustrate the face-off perfectly.  Those enlarged mandibles on their square-shaped heads can do a lot of damage.

Pavement ants are tiny, household pests that must have come with early settlers of North America, because they have been here since the early 1800s.  The must be hearty creatures because they can colonize some of the most uninhabitable-looking spaces.  The mounds of sand and dirt you might find between slabs of concrete in the summer are the work of pavement ants venting their underground nests.

pavement ant war

The day after I took the first photo above, an even larger eruption of pavement ants took place on the opposite side of the driveway.

Just another day in the life of a pavement any colony.

Incidentally, if you like cool photos of insects, Alex Wild’s photo gallery has some amazing ones.

12 thoughts on “Ant wars

  1. Of course they’re here, too. I figured they were expanding colonies but didn’t know about the warfare involved.

    • Yeah, I went out the next day and looked for remnants of the warfare and saw a lot of dead bodies. Not really a photogenic sort of picture to post on the blog though.

    • I think they might be fighting over space, and perhaps over food resources as well, but when the queen needs new chambers for her broods….the workers have to go looking for space.

    • It really did look chaotic out there, but isn’t it amazing how they face off with their opponents? There must really be some subtle chemical cues at work there.

    • yeah, I wish I had stuck around and really zoomed in on them. I didn’t even know what I was photographing at the time, until I looked at the photos on the computer.

  2. Hi Sue, lovely blog!

    I am from Purdue University, writing an article for Pest Control Technology on pavement ant territoriality and your last photo would be a great addition. Would it be possible to use it in the article? I would make sure to credit you and link to your blog.

    Best wishes,


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