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
Fire ant takes care of regular tasks (the main tasks in a colony are caring for the eggs/larvae/pupae, cleaning the nest, and foraging for food). However, "Solenopsis daguerrei" colonies contain no workers, as they are considered social parasites. Although most fire ant species do not bother people and are not invasive, "Solenopsis invicta", known in the United States as the red imported fire ant (or RIFA) is an invasive pest in many areas of the world, notably the United States, Australia, China and Taiwan. The RIFA was believed to have been accidentally introduced to these countries via shipping crates, particularly with Australia