How army ants' iconic mass raids evolved

Army ants form some of the largest insect societies on the planet. They are quite famous in popular culture, most notably from a terrifying scene in Indiana Jones. But they are also ecologically important. They live in very large colonies and consume large amounts of arthropods. And because they eat so much of the other animals around them, they are nomadic and must keep moving in order to not run out of food. Due to their nomadic nature and mass consumption of food, they have a huge impact on arthropod populations throughout tropical rainforests floors.