The World War of the Ants – The Army Ant

Army ant swarms generally avoid fighting each other because a clash between two lethal social armies would likely cause mutual annihilation, so natural selection favors passing, retreating, or other avoidance behaviors to prevent catastrophic losses.

Ant warfare occurs at many scales because a species' social organization—from small nomadic raiding groups to sprawling supercolonies—determines how far conflicts can spread and how long they persist.

If defenders can't seal nest entrances quickly during an attack, invaders can flood hidden chambers and consume tens of thousands of brood, which devastates the colony's capacity to recover.

Nomamyrmex esenbeckii can breach mature leafcutter nests because it specializes in consuming ant larvae and fields a particularly robust soldier caste that conducts coordinated long-column assaults capable of penetrating heavy defenses.

Leafcutter colonies resist invasions by fielding a specialized, massive soldier caste that locks onto and severs attackers at a wide frontline, but overwhelming attacker numbers can still swarm, surround, and ultimately break those defenses.

Some ant species survive army-ant raids by either evacuating brood to rebuild later or evolving worker morphologies that physically block nest entrances, because flight or entrance-barricading denies attackers access to vulnerable chambers.

Army ants are exceptionally dangerous because they abandon fixed nests to form coordinated nomadic swarms and long hunting columns whose overwhelming numbers swamp prey defenses before victims can react.

Ants became ecologically dominant because extreme cooperation—division of labor, cooperative construction, farming, and symbioses—lets many weak individuals together exploit niches no single ant could.