I love these leafcutter ants:
If I knew I would see so many interesting bugs I would have brought along a better camera! Here’s a better image I found online:
The genus around La Barra, Acromyrmex, doesn’t have quite the wild morphological swings as the more northern genus Atta, but still quite startling: 1mm workers working shoulder-to-shoulder with their sisters who are four times bigger.
In Uruguay they are considered a real pest. These ants are farmers, clearcutting almost any vegetation to take in to the colony as foodstock for their real meal: fungus. They create long, winding dirt tracks everywhere, sometimes running for hundreds of feet, destroying gardens and crops as they see fit.
As an experiment I disrupted one of these paths, scuffing it with my shoe until I had a barrier of dirt and grass. Gradually the traffic jam built up until there was a crowd of ants on both sides of the divide. Some ants lost their way, turning back the way they came (back to the colony or back to the work site). I felt a pang of guilt seeing this, wondering about the long, fruitless journey ahead for these lost ones. Not to worry: the press of bodies is such that anyone headed in the wrong direction is quickly turned around. I assumed all the empty-handed (empty-mouthed) workers needed to fix the barrier would be coming from the hive, but not so. It seemed that all along the path there are unladen ants ready to tend the trail itself.
Gradually the barrier was cleared, work resumed, and the silent march of millions of feet went on.
I was reminded of one the joys of traveling while writing this post. Uruguayans see these long dirt grooves carved in their lawns and fields and think: pest. As a traveler, my frame of reference is more temporary, less fixed. I can sit and stare and experiment and be amazed.