Leaf-cutter ants (Atta) are one of the most conspicuous and interesting types of ants found in rain forests. They can form huge colonies estimated to house more than a million individuals. The forest floor around their nests is usually completely bare. Very conspicuous foraging trails can run for dozens of meters through to forest. To the casual observer thousands of pieces of leaves are wiggle-wagging their way along these trails, each carried by a worker. Finally the leaf pieces disappear below ground into the ant nest (click here to view a short video segment complete with rain forest sounds). At the source tree other workers are cutting leaves into carriable sized pieces. Among the ants coming and going you can observe larger soldiers, a caste that protects the workers, and smaller riders being carried upon the leaf pieces, seen on both leaf pieces, a caste thought to protect the workers from parasitic flies. A fourth caste of trail cleaners also exists, and they can be identified by placing small bits of debris upon the tidy trails. The leaf pieces are carried below ground, processed, and used to grow a basidiomycete fungus which provides the ants with food. Our students have conducted experiments on caste sizes, optimal sizes of leaf pieces, leaf preferences, trail marking scents, and nest size correlations to trail lengths.