Tool use in a social insect and its implications for competitive interactions.

Four species of myrmicine ants, Aphaenogaster rudis, A. treatae, A. tennesseensis, and A. fulva, use pieces of leaf, mud, and sand grains as tools to carry soft foods from distant sources to the colony. Tools are tended on the food and removed by colony members without regard to which individual brought the tool. Food is gathered more efficiently by tool use than by internal transport. Tool-using behavior may increase the competitive ability of A. rudis in an interspecific dominance hierarchy.