Texas Leaf-cutting Ants, Atta texana

One night at Catalina State Park, near Tucson, Arizona, when I was hunting for Wolf Spiders, some motion caught my eye at the base of an Acacia tree near our campsite. There was a long line of medium-sized ants marching up and down the tree trunk. About one in 6 ants was carrying a small Acacia leaf. Acacia trees have compound leaves. Each leaflet turns out to be the perfect size for one ant to manage almost effortlessly. At the base of the tree was the entrance to their nest. Some ants carried their leaf into the nest, but most dumped their harvest at the entrance.

As you probably know, Leaf-cutting Ants don’t actually eat the leaves they harvest. Rather, the leaves are used as compost. They’re the growing medium for the particular species of fungus they cultivate. The mold consumes the leaves and the ants harvest the mold to feed their colony. Pretty sophisticated!