African Driver Ant

Dorylus driver ants form some of the largest insect societies on Earth — single colonies of 22 million workers have been documented. Unlike most ants, they do not build permanent nests; the colony is essentially an organism that moves continuously across the landscape, forming temporary 'bivouacs' (clustered ant-balls of millions of bodies) when it stops. Raids extend hundreds of meters from the bivouac, with worker columns up to 20 meters wide and many kilometers long. The columns sweep the forest floor, killing and eating any animal too slow or too small to escape — insects, spiders, lizards, frogs, birds, mice, snakes. The largest workers are 'soldiers' with massive curved mandibles strong enough to draw human blood; in some West African cultures the soldier mandibles are used as emergency surgical sutures, holding a wound closed by biting across the cut and then having the body twisted off so the head remains. Households across West and Central Africa welcome periodic driver-ant passages: families evacuate for an afternoon, return to homes thoroughly cleared of vermin. The ants are dangerous mainly to immobilized animals; livestock have been killed when penned, and historic reports of human deaths involve infants left unattended.