One of the most common sights in Costa Rica are lines of freshly cut leaves and flower petals marching their way down tree trunks and across the ground like a parade of natural confetti. These leaves and petals are carried by Leaf-cutter Ants (Atta cephalotes), which are abundant throughout the lowlands of Costa Rica.
Leaf-cutter Ants feed on fungus, which they cultivate in their underground nests. The cut pieces of leaves and flowers are not eaten by the ants, they are instead fed to the carefully tended fungus.
Most Leaf-cutter Ants are sterile female workers, and they are divided into several castes with different functions in the colony. The large workers (mediae) gather the leaves, and they are accompanied by small, hitchhiking minima workers.
The little minims ride on the cut leaves, but they are not lazy freeloaders, instead it is their job to protect their larger worker sisters from attacking parasitic Phorid Flies (Family Phoridae).