Army ants are a group of over 200 ant species that share a common lifestyle of nomadic hunting and raiding. They are found in tropical and subtropical regions of Africa, Asia, Australia and the Americas. Army ants are known for their aggressive and coordinated attacks on other animals, often overwhelming them with sheer numbers and ferocity. But army ants are not just destroyers; they also create a rich and diverse ecosystem around them, hosting hundreds of other species that depend on them for food, shelter and protection.
What are army ants?
Army ants are not a single taxonomic group, but rather a term that applies to several lineages of ants that have independently evolved a similar behaviour and ecology. This behaviour is called “legionary behaviour” or “nomadism”, and it involves constantly moving from one temporary nest to another, while foraging in large groups called “raids”. Army ants do not build permanent nests like most other ants; instead, they use their own bodies to form a living structure called a “bivouac”, where the queen and the brood are protected by a layer of workers. Army ants only stay in one place for a few days or weeks, before moving on to a new location.
The raids of army ants are impressive sights to behold. Depending on the species, army ants can have up to half a million workers in a single colony, and they can cover an area of several square meters when they forage. Army ants use chemical trails and tactile signals to communicate and coordinate their movements. They prey on a variety of animals, including insects, spiders, worms, scorpions, centipedes, snails, lizards, frogs, snakes, birds and even small mammals. Army ants use their powerful mandibles to cut and tear their prey into pieces, which they then carry back to the bivouac to feed the queen and the larvae.
Why are army ants important?
Army ants are not only formidable predators, but also vital components of the tropical and subtropical ecosystems they inhabit. Army ants create a complex web of interactions with other organisms, both as enemies and as allies. Many animals have evolved adaptations to avoid or escape the raids of army ants, such as camouflage, mimicry, speed or defensive chemicals. Some animals even use the raids as opportunities to feed on the fleeing prey or the leftovers of the ants. These animals are called “ant-followers” or “myrmecophiles”, and they include birds, mammals, reptiles, amphibians and insects.
Some ant-followers have developed a close relationship with army ants, such that they cannot survive without them. These animals are called “obligate ant-followers”, and they include over 300 species of insects that live exclusively in association with army ants. Some of these insects mimic the appearance or behaviour of army ants, while others provide services to the ants in exchange for food or protection. For example, some beetles help the ants to clean their bivouacs by removing dead bodies or parasites, while some flies lay their eggs on the ant larvae and provide them with extra nutrients.
How can we protect army ants?
Army ants are threatened by habitat loss and fragmentation due to human activities such as logging, agriculture and urbanization. Army ants need large areas of undisturbed forest to maintain their nomadic lifestyle and their diverse entourage of ant-followers. When forests are cleared or degraded, army ants lose their food sources and their shelter, and they become more vulnerable to predators and parasites. Moreover, army ants play an important role in regulating the populations of other animals and recycling nutrients in the soil. Losing army ants would have negative consequences for the whole ecosystem.
To protect army ants and their associated biodiversity, we need to conserve their natural habitats and reduce human impacts on them. We also need to raise awareness about the ecological value and beauty of these amazing insects. Army ants are not just mindless killers; they are complex social organisms that create life wherever they go.