The Brutal World of Ant Slavery: The Polyergus and Their Victims

The world of ants is not only a battleground of fierce competition but also one of unimaginable cruelty. Among the numerous species of ants, some have taken extreme measures to ensure their survival—by enslaving other ant species. This practice, the most extreme form of division of labor, is employed by around 50 species of ants, but none are more notorious than the Polyergus, the slaver ants.

Polyergus ants, generally measuring 4 to 10 millimeters with brown to black bodies and sickle-shaped mandibles, have perfected the art of slavery. They are so specialized in this gruesome practice that they’ve lost the ability to care for themselves. They do not build nests, feed themselves, or even clean; their sole purpose is to raid, steal, and enslave. In a single colony, Polyergus ants, led by a queen, control thousands of slaves, making up 82-90% of the colony's population.

The process begins on a calm summer morning when a Polyergus scout identifies a target—a thriving Formica ant colony. The scout returns and releases pheromones to signal other raiders, who form an organized column up to 10 meters long. As the raiding party attacks, the Formica ants, though numerous and formidable, are thrown into confusion, unable to mount an effective defense. The Polyergus use chemical warfare, releasing propaganda pheromones that cause panic among the defenders. They want their victims to survive, as the slaves they capture will serve them for future generations.

After penetrating the Formica nest, the raiders target the colony’s most valuable possession: the brood. The stolen pupae are carried back to the Polyergus colony, where they will grow up to become slaves. Some victims are consumed, but most are put to work, tending to the needs of their new masters. The raid is over in about an hour, and the Formica ants are left to recover, attempting to rebuild their numbers as a new generation of victims is harvested.

The concept of slavery among ants is complex and deeply tied to chemical communication. Unlike other ants, slave-making ants struggle to communicate with each other. As a result, when Polyergus steal the brood of other species, they use pheromones to imprint their identity onto the stolen ants. This chemical manipulation makes the slaves believe they belong to the Polyergus colony, and they serve their captors without question, even mistaking free ants as enemies.

Polyergus colonies rely on the constant supply of new slaves to survive, as their workers are incapable of performing basic tasks. Without slaves, a new queen cannot establish a colony. There are two main strategies for creating new slave colonies. One method involves a Polyergus queen following a raiding party to kill the Formica queen and take over the colony. However, this is risky, as other Polyergus colonies often raid each other, and a new queen may be defeated by rival ants.

The second strategy is even more brutal. A young Polyergus queen will find a Formica colony far from her birthplace and attack it. Using a powerful appeasement pheromone, she causes the defending ants to scatter, allowing her to find and kill the Formica queen. After defeating the queen, she covers herself in her victim’s pheromones, and the workers from the Formica colony begin to serve her as if she were their own queen. If she manages to kill all the queens, the Polyergus queen will begin laying eggs, which will hatch into new Polyergus ants. These new ants will continue the cycle of raiding and enslavement.

The world of the ants is a constant war, with billions of individuals waging a never-ending struggle for survival. For the Polyergus ants, raiding and enslaving are not just part of their life—they are essential for their continued existence. In this dark and twisted battle of nature, there is no room for surrender, only the relentless pursuit of dominance.