Published by BuzzSkito Mosquito & Tick Control
Published October 7, 2026 · Drafted with AI assistance and fact-checked against the sources listed below
What are army ants?
Army ants are ants that hunt only in groups, keep no permanent nest and move the whole colony from site to site with a wingless queen. Entomologists call that set of traits the army ant syndrome. A 2019 genetic study in Systematic Biology defines it as obligate collective foraging, frequent colony relocation and highly specialized wingless queens, and reports that no army ant species is known to lack any part of it. The same paper places all army ants in one subfamily, the Dorylinae, and describes them as spread through the warm temperate and tropical regions of the world.
The name therefore covers a way of life shared by many species, not a single insect. A Swarthmore College Bulletin profile of army ant specialist Carl Rettenmeyer counts about 155 species in the Western Hemisphere and possibly 100 more in Asia and Africa. They behave very differently from the common ants found in and around US homes.
| Trait | What army ants do | Source |
|---|---|---|
| Group hunting | Workers forage only in groups and never alone, unlike many other ant species | Borowiec 2019 |
| Nomadism | Nests are temporary, and in some species the colony cycles between nomadic and stationary phases | Borowiec 2019 |
| Wingless queen | The queen cannot fly, travels on foot and is adapted to produce enormous quantities of brood | Borowiec 2019 |
| Colony fission | A colony reproduces by splitting; a queen never founds a new colony alone | Borowiec 2019; Kronauer and colleagues 2011 |
| Winged males | Males leave on the wing to mate with a young queen in another colony | Kronauer and colleagues 2011 |
The traits that define an army ant, from the two research papers linked on this page.
How does an army ant colony live without a permanent nest?
It camps in a temporary shelter called a bivouac and moves on as its young develop. In Eciton burchellii, a swarm-raiding species of the American tropics, the bivouac is built from the ants themselves: the University of Michigan's Animal Diversity Web account describes living workers clinging together by specialized hooks on their feet, and notes that colonies occasionally bivouac in trees several yards above the ground. The Swarthmore profile, which does not tie these figures to a single species, adds that a typical colony builds its bivouacs among tree roots or inside hollow trunks, moves at night over distances of up to 100 yards at about 20 yards per hour, and travels about nine miles a year.
US army ants are less showy. University of Tennessee Extension reports that Neivamyrmex nigrescens settles before sunrise into a recently raided ant nest or a natural cavity, and that during its settled phase it may stay under stones, in the ground or in an abandoned ant nest.
What are the nomadic and stationary phases?
They are the two halves of a repeating cycle tied to the age of the colony's young. In the University of Tennessee's account of N. nigrescens, the nomadic phase starts when new workers emerge from their pupae. The colony then raids every night and carries its larvae to a new temporary site each time, for about 3 weeks, until the larvae pupate. For roughly the next two weeks it stays in one place, the statary phase. Raids may continue then, but the entire colony does not take part.
Animal Diversity Web describes the same pattern in E. burchellii: major raids every day that end in a change of nest site during the nomadic phase, then less vigorous and less frequent raids from a fixed site, with the queen laying a new batch of eggs about every three weeks. The Systematic Biology paper describes these cycles of stationary and nomadic phases as something colonies undergo in some army ant species.
Which army ants are the best known?
The best known are Eciton burchellii of the American tropics and the Dorylus driver ants of Africa, because both raid in the open in very large numbers. That fame is a little misleading. The Systematic Biology study points out that what is known about the ecology and behavior of this subfamily comes mostly from the minority of species that forage conspicuously above ground.
| Army ant | Where it lives | Colony size | Known for |
|---|---|---|---|
| Eciton burchellii | Tropical Central and South America | 100,000 to 2,000,000 adults | Fan-shaped swarm raids followed by antbirds; a bivouac made of living workers |
| Driver ants (Dorylus) | Forests of sub-Saharan Africa; at least one species also in savanna | More than 10 million | The largest colonies cited here; swarm raids |
| Neivamyrmex nigrescens | United States, including Tennessee | Hundreds of thousands | Night raids on other ants' nests in columns up to nearly 300 feet long |
| Aenictus | Asia, Africa and Australasia | Not given in these sources | Old World genus that is superficially similar to Neivamyrmex in appearance and biology |
Figures from Animal Diversity Web, Kronauer and colleagues (2011), University of Tennessee Extension and Borowiec (2019). Colony sizes are estimates.
E. burchellii workers range from about 1/8 to 1/2 inch (3 to 12 mm) and have long, pointed, hook-shaped mandibles, according to Animal Diversity Web. The raiding ants spread into a dense fan-shaped swarm that stays connected to the bivouac by a single column, and that column can stretch more than 650 feet (200 meters). Sources differ on how wide a swarm gets: Animal Diversity Web says several yards across for this species, while Rettenmeyer, describing army ant swarm raids without naming a species, told Swarthmore's magazine that one can be about 50 yards wide. On colony size, Animal Diversity Web gives 100,000 to 2,000,000 adults, and the Swarthmore profile describes migrating columns of up to one million ants.
For driver ants, a 2011 paper on East African species in Frontiers in Zoology calls them a prominent feature of Afrotropical forests, meaning those of sub-Saharan Africa, and prime invertebrate predators, with colonies of more than ten million individuals. Of the two species it studied in Kenya, Dorylus wilverthi is essentially restricted to intact rainforest, while D. molestus also lives in savanna and open farmland. For numbers on a larger scale, a separate guide explains how researchers estimated the total number of ants on Earth.
Where do army ants live?
Army ants live in warm temperate and tropical regions on several continents, with different genera in the Americas than in Africa and Asia. The Systematic Biology study lists five genera of New World army ants: Cheliomyrmex, Eciton, Labidus, Neivamyrmex and Nomamyrmex. The Old World has Aenictus and the Dorylus driver ants, plus a poorly known African genus, Aenictogiton, that is assumed to be an army ant without direct evidence of the behavior.
- The Americas. Eciton burchellii lives in the tropical regions of Central and South America. Neivamyrmex arose in the American tropics about 13 million years ago, and at least one branch moved into and diversified in the southern part of North America.
- Africa. Driver ants are a feature of forests south of the Sahara, and at least one species also uses savanna and open farmland.
- Asia and beyond. Aenictus originated in the Indomalayan region of tropical Asia and spread into Africa and Australasia, with some species ranging into the temperate zone to the north.
- Madagascar. The island has seven genera from the same subfamily but no true army ants.
Are there army ants in the United States?
Yes. The US has native army ants in the genus Neivamyrmex, with the records cited here running from Arizona and New Mexico across Texas and Louisiana to Tennessee, and north to Kansas. They are easy to miss, because the raids these sources describe take place at night or below ground. The University of Tennessee's extension entomologist calls it a genus not encountered every day: only 19 of nearly 4,100 submissions to the university's Urban IPM Lab between 1997 and February 2023 were Neivamyrmex.
- Tennessee. The lab identified N. nigrescens and N. opacithorax, and N. carolinensis is also recorded in the state.
- Texas, Louisiana, Arizona, Kansas and New Mexico. A Mississippi Entomological Museum field note lists these states, along with Mexico and Guatemala, for N. fallax, a species about which little is known.
- Seen above ground. The same note, citing a 1985 review of the army ants of the United States, names six species whose raids and migrations often take place above ground: N. californicus, N. harrisii, N. nigrescens, N. opacithorax, N. pilosus and N. texanus.
The museum note explains why the group stays obscure: many army ant species seem to avoid direct sunlight or live mainly below ground, so their habits are not well known. None of the sources here gives a complete state-by-state list or a total species count for the US, so treat the states above as examples and not as the full range.
What do US army ants look like?
Workers have very small eyes, a two-segmented waist, a sting and 12-segmented antennae with no club at the tip. Those are among the features the University of Tennessee newsletter uses to tell the genus apart. Because they sting, they are occasionally mistaken for fire ants, but the newsletter notes that fire ant antennae have ten segments ending in a two-segmented club. If stinging ants around a mound are the concern, compare the fire ants and other red ants found in the US.
The males are the caste people notice. They are winged, wasp-like and attracted to lights, and the first one sent to the Tennessee lab, in 1997, was about 0.4 inch (10 to 11 mm) long. In Tennessee, N. carolinensis males fly from mid-May to early June, N. nigrescens from mid-August to mid-November and N. opacithorax from late August to early December. Indoor flights often set off termite scares. The male's single-segmented waist rules that out, and a separate guide shows how to tell winged ants from termite swarmers. Queens have no wings and are rarely seen.
What should you do if army ants turn up in a house?
Often nothing, in the warmer months, beyond keeping your hands off them and waiting. The University of Tennessee reports that colonies may settle beneath basement floors or in and around foundation walls. It describes one colony found behind kitchen wall paneling in January 2023 and workers found in a washing machine's water intake valve one June.
When a colony is found indoors during the warmer, active months, the newsletter says no management effort is often needed, because the colony disperses once it enters the nomadic stage. Afterward, repair cracks in the foundation or slab and do other pest-proofing so the ants cannot return. Workers can sting, so avoid contact. Winter is a different case: the newsletter's author doubts the January colony was still producing brood, which made a move unlikely, and that colony was treated instead of being left alone.
Ants that trail day after day to food on a counter do not match any behavior these sources describe for army ants, and they point to an ordinary household species. For that problem, see why baiting works better than spraying on household ant trails. Large black ants coming out of woodwork are a separate problem again, covered in how to find a carpenter ant nest inside a structure.
What do army ants eat?
Army ants eat other animals, mainly insects and other arthropods, and many species specialize in raiding the nests of other ants. The Mississippi Entomological Museum note says Neivamyrmex species feed almost exclusively on animal prey, typically the brood of other ant species. The University of Tennessee agrees that ants appear to be the primary food of N. nigrescens, with other insects taken too, and says its night columns can reach nearly 300 feet as they capture insects and raid ant nests.
The museum note records one such raid in detail. On the evening of June 27, 2006, near Alpine in west Texas, N. fallax workers emerged from three holes in the ground and attacked a colony of Solenopsis xyloni, a member of the fire ant genus, that appeared to be moving its nest. The air temperature was about 84°F (28.8°C). The army ants seized eggs and pupae, sometimes straight from the jaws of the other ants, and carried off winged males and females as well. By the next morning there was no sign of either species.
In the tropics the menu is broader. Animal Diversity Web lists the brood of wasps and other ants, cockroaches, crickets, grasshoppers, beetles, scorpions and tarantulas among the prey of E. burchellii, whose workers cooperate to catch, subdue and carry what they take. Rettenmeyer told Swarthmore's magazine that army ants are the most important predators in a tropical forest, because by his account a single colony can consume half a million animals a week.
A raid feeds more than the ants. Flocks of antbirds follow the swarm to eat the arthropods it flushes out, not the ants, and Rettenmeyer said 46 antbird species depend on E. burchellii alone for food. The profile refers to more than 300 species that depend entirely on army ant colonies for survival. For the diets of the ants people meet at home, see what ants eat, from sugar and honeydew to seeds and other insects.
Are army ants dangerous to people?
Not in the way films and adventure stories suggest. Army ants bite, and some species sting, but the sources behind this page describe hunters of insects and other small animals, and none reports a colony killing a healthy person. The Swarthmore profile says the ants' reputation as ferocious killers is largely the product of science fiction, and it gives Rettenmeyer's own verdict: they do bite but cause no serious damage.
| Myth | What the sources say |
|---|---|
| Army ants strip people and large animals to the bone | Animal Diversity Web says the mandibles of E. burchellii lack a good cutting edge, so prey too big to carry that cannot be pulled apart is left behind. It notes attacks on snakes, lizards and nestling birds, but no accounts of vertebrate prey being carried back to the bivouac. |
| A colony on the march cannot be avoided | The Swarthmore profile puts a relocating colony's pace at about 20 yards per hour, and Animal Diversity Web says E. burchellii does not frequently come into contact with people. |
| Army ants are only a jungle insect | Native Neivamyrmex species live in the US, with records from Tennessee to Arizona. |
| Every army ant marches in the open | N. nigrescens raids at night, and many army ant species avoid sunlight or live mainly underground. |
Each row paraphrases a source linked on this page.
That does not make them harmless to handle. Animal Diversity Web says E. burchellii has a painful sting and defends its bivouac aggressively. In the US, the University of Tennessee cites a regional ant reference that lists three Neivamyrmex species as occasional stinging pests, and it advises avoiding contact with workers. A separate guide covers which US ants bite, which sting and when a reaction needs medical care.
For African driver ants, the evidence gathered here is thinner. The Frontiers in Zoology paper is a genetics study and does not address injuries to people, and none of the sources cited on this page documents a human death, so stories of that kind should be treated as unverified here.
The same sources treat army ants as useful. Animal Diversity Web says E. burchellii can be very beneficial in removing agricultural and household insect pests, and the Swarthmore profile calls army ants beneficial to the environment and to people.
Did army ants evolve once or more than once?
Researchers disagree, and the newer genetic evidence favors more than once. The Systematic Biology paper summarizes the earlier view, from a 2003 study, that the army ant syndrome arose a single time about 100 million years ago. Its own analysis, built on 2,166 genetic regions from 155 species in all 27 genera of the subfamily, mostly supports separate origins in the Old World and the New World, though the author notes that some relationships shift with the analytical method used.
The dates in that study are younger than the older estimate. The five New World army ant genera share an ancestor about 28 million years ago (range 20 to 37 million), the driver ant genus Dorylus dates to about 16 million years ago, and the conspicuous above-ground raiders in Dorylus and Eciton diversified within the last 5 to 6 million years. The author cautions that the early dates carry considerable uncertainty. Both views agree on one thing: once the syndrome evolved, no known lineage gave any part of it up.
How do army ants compare with other remarkable ants?
Army ants are remarkable for how the colony lives, not for the power of any single worker. The ant best known for its sting is a different insect, and the bullet ant guide covers its sting, size and range. Where army ants carry their young from camp to camp, honeypot ants turn some of their own workers into living food stores. A third oddity is not the ant's doing at all: the fungus behind so-called zombie ants takes over the behavior of the ants it infects.
Frequently Asked Questions
Can army ants kill a human?+
None of the scientific sources used for this page reports an army ant colony killing a healthy person. Carl Rettenmeyer, an entomologist who specialized in army ants, said they bite but cause no serious damage, and their fearsome reputation is attributed largely to science fiction. The University of Michigan's Animal Diversity Web notes that Eciton burchellii has been seen attacking snakes, lizards and nestling birds, but that there are no accounts of vertebrate prey being carried back to the bivouac, and that prey too large to carry or pull apart is left behind. Army ants can still bite, and some sting, so they should not be handled.
Do army ants bite or sting?+
Both, depending on the species. Animal Diversity Web says the tropical species Eciton burchellii has a painful sting and defends its bivouac aggressively, although it does not often come into contact with people. In the United States, University of Tennessee Extension says Neivamyrmex workers can sting and advises avoiding contact, and a reference on southeastern ants lists three Neivamyrmex species as occasional stinging pests. Anyone who has a strong reaction to a sting should contact a healthcare provider.
How many ants are in an army ant colony?+
It depends on the group. Animal Diversity Web gives 100,000 to 2,000,000 adults for a colony of Eciton burchellii in the American tropics, and a Swarthmore College profile of army ant specialist Carl Rettenmeyer describes migrating columns of up to one million ants. African driver ants in the genus Dorylus are larger still, with colonies of more than ten million individuals according to a 2011 paper in Frontiers in Zoology. For the US species Neivamyrmex nigrescens, University of Tennessee Extension says a colony may contain hundreds of thousands of members.
Are army ants blind?+
Their eyesight is poor at best, and sources describe it differently. The Swarthmore College Bulletin's profile of Carl Rettenmeyer calls army ants blind and dependent on chemical trails for direction, while Animal Diversity Web says Eciton burchellii workers have eyes with a single facet. For the US genus Neivamyrmex, University of Tennessee Extension describes the workers' eyes as very small, resembling the simple eyes called ocelli. Neivamyrmex males are easier to notice because they have wings, are attracted to lights and look more like wasps than ants.
Do army ants have a queen?+
Yes. Each colony has a queen, but she is unlike most ant queens. Army ant queens are permanently wingless, never make a mating flight and do not start new colonies alone, according to a 2011 paper in Frontiers in Zoology. Instead a colony reproduces by splitting, and winged males fly in from other colonies to mate with a young queen. A 2019 study in Systematic Biology adds that the queens travel on foot and are adapted to produce enormous quantities of brood.
Sources
- Convergent Evolution of the Army Ant Syndrome and Congruence in Big-Data Phylogenetics — Systematic Biology (Oxford University Press), via the NSF Public Access Repository
- New World Army Ants, Neivamyrmex spp. (Insec(tc)ure newsletter, Volume 4, Issue 2) — University of Tennessee Extension, Urban IPM Lab
- Eciton burchellii — Animal Diversity Web, University of Michigan Museum of Zoology
- Observations of Neivamyrmex fallax Borgmier and Solenopsis xyloni McCook (Hymenoptera: Formicidae) — Marginalia Insecta, Mississippi Entomological Museum, Mississippi State University
- Hybridization in East African swarm-raiding army ants — Frontiers in Zoology (BioMed Central, Springer Nature)
- Entomological “Ant”ics — Swarthmore College Bulletin
How this guide was made: it was researched and drafted with AI assistance from the sources listed above. A second, independent AI pass then checked each factual claim against those sources. Found an error? Email support@buzzskito.ca.