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
Green-head ant they prefer. This suggests that the cost of moving to a suitable nesting site outweighs the benefits of moving to a larger rock. A large expenditure of energy is required for a move: scouts must first find a suitable site, brood must be transported safely, and the colony is exposed to an increased risk of predation. Nest abandonment by the green-head ant varies, but peaks during summer. Like other temperate species, activity in colonies is greatly reduced during the colder months, which may be the reason there is a high proportion of nest abandonment during summer. Nests abandoned by green-head