With their scissor-like jaws, leaf-cutter ants carve out crescent-shaped pieces of leaves, which they then carry back to their underground nests. The leaf bits are carried above their heads like green umbrellas, giving them the nickname “parasol ants.” There are fourteen different species of leaf-cutter ants in the Amazon.

The ants will select only certain trees, or cut only young leaves or old leaves, or green fruits; sometimes they cut only flowers. Their choice may be related to the presence of toxic chemicals in the leaves. Many tropical plants have evolved such poisonous or distasteful chemicals as an adaptation to protect themselves from leaf-eating organisms.

The ants do not feed on the leaves directly; instead, the crushed leaves are used to grow a special fungus in certain of the underground chambers, which is then eaten by the ants. Some biologists believe that leaf-cutting ants are the Amazon's major herbivores, damaging more leaves than any other leaf-eater. Ants and termites as a collective group make up about 30% of the animal biomass in a tropical rain forest.

Ants are social insects, and leaf-cutter ants have one of the most complex social organizations. They are organized by a division of labor. The queen lays the eggs, so the growth of the colony is dependent on her. The “workers” are the labor force, with specific tasks according to size and age. The very small ants take care of the fungus. The bigger ones that are strong enough cut the leaves. And then there are the soldiers. They cut only the very tough leaves, but mostly they’re involved in mass defense. If an enemy invades their nest, thousands of soldiers go outside the nest to defend the colony. Many of them die, but the nest is saved.

Learn more about leaf-cutter ants.