Argentine ant paralleled only by human society", and had probably been spread and maintained by human travel. They have been extraordinarily successful, in part, because different nests of the introduced Argentine ants seldom attack or compete with each other, unlike most other species of ant. In their introduced range, their genetic makeup is so uniform that individuals from one nest can mingle in a neighboring nest without being attacked. Thus, in most of their introduced range, they form supercolonies. "Some ants have an extraordinary social organization, called unicoloniality, whereby individuals mix freely among physically separated nests. This type of social organization is
Red harvester ant the nest as a result of an increase in successful returning foragers. Relative abundance of food available is gauged by the average time spent foraging per seed, rather than the distance traveled to find each seed. Foragers take less time when food is more abundant. Faster foraging signals faster rates of outgoing foragers, maximizing the harvest of food relative to the abundance in the area. Seeds are used as a source of water for ants, and are often kept in the nest for a few months to several years. Interspecies competition exists between harvester ant populations, presenting challenges to successful