The sidewalk battles have begun

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Tetramorium pavement ants from neighboring colonies engaged in battle.

Spring has arrived in full! The birds are singing, the tulips blooming, and the trees are greening.

But, whatever. As an ant guy my favorite indication of the season is much more chitinous:

massive urban ant warfare

The Tetramorium pavement ants that live under every sidewalk in town have begun their spring expansion. When colonies meet, each dispatches as many workers to the front as they can muster. The larger colonies push out harder, while the weaker one are forced back into smaller territories more appropriate to their numbers. The battles can last for days.

I’ve seen several of these sprawling conflicts this week, within a few blocks of my house, and I imagine elsewhere in their range the pavement ant action is also heating up. If you live in the midwest, atlantic coast, or northeast, keep an eye out along urban walkways for what seems like a shimmering oil slick. The spectacle is well worth watching.

11 thoughts on “The sidewalk battles have begun”

  1. Out in Utah right now the sidewalks are no-ants-land. Last month during the first really warm, sunny days we had the first series of pavement battles.

  2. I just saw my very first Tetramorium battle in Normal, IL, and stopped everyone in the family reunion to see that. Super exciting!

    1. Flavia Esteves

      And it seems I am so excited that could not comment your post properly, and pressed submit without sign my name. p.s. Parabéns por your daughter!!

  3. Julie Stahlhut

    We posted a brief video of a Tetramorium fight to YouTube about seven years ago. I still occasionally get comments on it. A disturbing percentage of the comments advocate addressing the phenomenon with homemade backyard-scale firebombs. Yikes!

  4. I’ve watched a few of these, but I guess I’m not observant enough; I can never tell which side is which, or even where the home nests and territorial boundary are.

  5. The Tetramorium pavement ants that live under every sidewalk in town have begun their spring expansion. When colonies meet, each dispatches as many workers to the front as they can muster. The larger colonies push out harder, while the weaker one are forced back into smaller territories more appropriate to their numbers. The battles can last for days.

  6. The Tetramorium pavement ants that live under every sidewalk in town have begun their spring expansion. When colonies meet, each dispatches as many workers to the front as they can muster. The larger colonies push out harder, while the weaker one are forced back into smaller territories more appropriate to their numbers. The battles can last for days.

  7. Tetramorium colonies used to have their battles on the kitchen floor when I was a child. My parents would freak out! When I started studying ants in grad school, I immediately knew what the family ants were. By then, the ants had learned they were supposed to fight on sidewalks, and I was able to collect a battle royal by anesthetizing them with CO2. When they woke up, the didn’t continue fighting. They couldn’t tell each other apart. I also never observed any dismantled individuals. I assumed they didn’t kill each other, but rather rubbed against each other during the melee until they all assumed the odor of the larger colony and then they all joined together. It would make sense that conserving as many workers as possible would increase the fitness of the species. I once read that the queen of the loosing colony was assassinated afterwards.

  8. James C. Trager

    The Asian species that lives in a 100 or so mile radius around St. Louis Tetramorium tsushimae, also does this, but to a lesser extent. They are polygyne, and also apparently on the way to being unicolonial, so I’m not sure why they bother, and I wonder if queen assassination occurs in them, too? One thing is for sure, this species whupps the monogyne Tetramorium “sp. E” to oblivion where the two come together (and it’s hard on a lot of native ants, too).

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