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.