Ants are conspicuous components of most terrestrial ecosystems. Ants are important predators, scavengers, granivores, and in the new world, herbivores. Ants also engage in an astonishing array of associations with plants and other insects, and can act as ecosystem engineers as agents of soil turnover, nutrient redistribution, and small-scale disturbance. Over 15,000 species of ants have been described, and more than 200 have established populations outside of their native ranges. A small subset