Army Ant (Eciton burchellii)

InsectAntNeotropical

Overview

Eciton burchellii is the best-known of the New World army ants, a species of Central and South American forests whose colonies can contain hundreds of thousands of workers. Unlike most ants, it builds no permanent nest.

Instead the colony forms a bivouac: a temporary nest constructed from the bodies of the ants themselves, which link legs to form a living structure around the queen and brood, often beneath a log or in a tree buttress.

The colony alternates between a nomadic phase, moving almost daily and raiding heavily, and a stationary phase while the queen lays and the larvae develop. Its raids are the defining spectacle: a swarm front advancing across the forest floor, flushing invertebrates ahead of it.

Habitat & Range

Eciton burchellii lives in humid lowland tropical forest from Mexico through Central America into South America. Colonies need extensive intact forest floor to raid across, and they shift bivouac sites frequently during the nomadic phase, using sheltered spots such as hollows beneath fallen trunks, cavities and tree buttresses.

Diet

Army ants are predators. Swarm raids take a wide range of arthropods — spiders, crickets, cockroaches, scorpions, other ants and their brood — and occasionally small vertebrates that cannot escape. Prey is overwhelmed by numbers, cut up, and carried back along the raid columns to the bivouac.

Behavior

A raid begins as a fan-shaped swarm front spreading across the forest floor, with columns feeding prey back to the bivouac behind. Workers are strongly differentiated by size, from small workers to large soldiers with prominent hooked jaws. The colony cycle alternates between nomadic and stationary phases tied to brood development. Army ants also build living bridges, workers linking bodies to span gaps so the column can cross.

Human Interaction & Conservation

Army ant swarms are one of the most striking phenomena of Neotropical forests, and they support an entire community of associated animals. Ant-following birds — antbirds, woodcreepers and others — track raids not to eat the ants but to catch the insects fleeing ahead of the swarm, and some are so dependent on this that they are considered obligate ant-followers. Butterflies feed on the droppings of those birds, and various arthropods live inside the bivouac. Because colonies need large areas of continuous forest, they are sensitive to fragmentation, and their loss cascades to the species that depend on them. This profile offers no pest-control or handling guidance.