Army ants live across the tropical regions of the Americas, Africa, and Asia. They fall into two major groups on opposite sides of the world: New World species in Central and South America, and Old World species (often called driver ants) spanning sub-Saharan Africa into Southeast Asia. Their range covers a surprisingly wide belt of the planet, though they concentrate most heavily in lowland tropical forests.
New World Army Ants in the Americas
The most studied army ants belong to the genus Eciton, which ranges from Mexico to Argentina. Twelve described species and several subspecies occupy this stretch, with the greatest diversity in the dense lowland forests of Central and South America. The most well-known species, Eciton burchellii, lives in heavily forested, low-elevation regions where it functions as a top predator and keystone species, shaping the biodiversity of the entire forest community around it.
These ants thrive in continuous tropical forest. They need large, connected areas of canopy cover to sustain their enormous colonies, which can number in the hundreds of thousands. Deforestation and habitat fragmentation have started to put pressure on populations, particularly where once-continuous forest has been broken into isolated patches. Peru, Brazil, Costa Rica, Panama, and southern Mexico are all strongholds for New World army ants, with the densest populations in Amazonian and Central American rainforests.
Old World Driver Ants in Africa and Asia
On the other side of the Atlantic, the genus Dorylus fills a similar ecological role. Commonly called driver ants, these species range from sub-Saharan Africa through North Africa and Asia Minor all the way to Borneo in Southeast Asia. That is a far broader geographic spread than most people expect, covering everything from the Congo Basin to parts of China, India, Myanmar, and Sri Lanka.
Africa is the center of driver ant diversity. The continent harbors the highest number of Dorylus species and is home to the species that forage on the surface and through leaf litter, the ones most likely to form the dramatic raiding columns people associate with army ants. Asian populations tend to be less conspicuous, with many species foraging primarily underground.
Habitats That Support Army Ants
Across both hemispheres, army ants concentrate in warm, humid environments. Tropical rainforests at low elevations are the classic army ant habitat. These forests provide the dense ground cover, abundant prey, and stable temperatures that massive nomadic colonies depend on. In the Americas, Eciton species stick almost exclusively to these conditions.
Dorylus species in Africa are more flexible. While rainforest is prime habitat, some species also live in tropical savannas, woodland edges, and even semi-arid regions of North Africa. This ecological flexibility helps explain why driver ants span a wider range of latitudes and biomes than their American counterparts. Some Dorylus species have adapted to drier conditions by spending most of their time in underground tunnels, surfacing only during raids.
Why You Won’t Find Them in Temperate Regions
Army ants are absent from Europe, most of North America, and other temperate zones. Their colonies are enormous and constantly on the move, requiring a year-round supply of invertebrate prey that only tropical ecosystems reliably provide. Cold winters would be lethal: army ants don’t build permanent nests with the insulation needed to survive freezing temperatures, and their nomadic lifestyle depends on being able to march continuously.
The northernmost limit in the Americas is southern Mexico. In the Old World, some Dorylus species reach North Africa and parts of the Middle East, but these are typically subterranean species that avoid surface temperature extremes. No army ant species has established populations in the continental United States, despite occasional sensationalized reports. The closest you can get to army ants in North America is a handful of related species in the southern U.S. that share some behavioral traits but form much smaller colonies and lack the massive surface raids characteristic of true army ants in the tropics.
How Colony Size Shapes Their Range
A single Eciton burchellii colony can contain over 500,000 workers. Dorylus colonies in Africa can be even larger, with estimates reaching into the millions. Colonies this size need to sweep through large areas of forest floor to find enough food, which is why army ants require vast, connected habitats. A small forest fragment simply cannot sustain them.
This is also why army ants serve as indicators of ecosystem health. Where army ant populations are thriving, the surrounding forest is generally intact and biodiverse enough to support their raiding lifestyle. Where forests have been cut into small patches, army ant colonies decline or disappear entirely, even if the remaining forest looks healthy on the surface. Their presence tells ecologists something important about the landscape they occupy: it is large enough, connected enough, and productive enough to feed one of the most demanding predators in the insect world.