Neivamyrmex melanocephalus army ants initiating a live-ant bridge with their own bodies. Here two ants lean against each other while a third starts to climb. Sycamore Canyon, Arizona, USA

Neivamyrmex nigrescens army ants are predators of other ant species. Here an army ant worker carries a paralyzed prey ant back from a successful raid on an Aphaenogaster nest. Huachuca Mountains, Arizona, USA