The Argentine Ant (Linepithema humile) is a species of ant from South America.
This species is an alien to Britain, originating of Argentina, Uruguay, south Brazil and Paraguey, and is an alien to Europe including Britain, introduced by humans. This small ant have workers which are about 3mm in length, while the queens are two to four times their length. Workers can fit into cracks only a mm wide, and will build nests in the groud, cracks in walls, wood, leaf litters, and even in buildings, as well as taking over abandoned nests from other species.
These species are doing so well, because, unlike other ants, they will not compete with others of the same species, and won't attack another Argentine Ant colony. These species compete with our native ants, are a pest.