identification of the species is complicated by interspecies breeding and the existence of a number of cryptic species in its native range. Currently it is believed that nominal S. saevissima actually comprises at least 5 cryptic species (i.e. of identical morphology) that can be separated using chemical characters. Colony Social hierarchy Unlike S. invicta, which has been identified as unicolonial ants (polygynous colonies coalescing into one giant supercolony in which there is no aggression between workers of the various colonies), S. saevissima forms monogynous colonies, in which each colony has only one fertile female: the queen and the workers are aggressive towards other colonies. The stable inhabitants of the nest, similar to those of the other fire ants, include one reproductive queen and hundreds to thousands of sterile daughter workers. Occasionally, the nest would be inhabited by a few virgin queens and several drones (male ants). The virgin queens must soon leave the nest to establish their own colonies and the drones only live long enough for the mating flight and then they die afterwards. The job of the queen is to reproduce; the job of the drones is to pass on their genes through mating with the queen; and the jobs of the workers are to build, repair, and protect the nest, to care for the brood, and to feed everyone. Eusociality S. saevissima, similar to the other social insects in the order Hymenoptera, is eusocial: an extreme form of kin selection in which members of a group willingly give up their reproductive abilities in favor of the reproductive success of their close relatives. For S. saevissima, the workers are all sterile female daughters who dedicate their lives to the caring and protection of their future sisters: the broods of the fertile queen (their mother). In eusociality, the sterile ants often perform specialized tasks to effectively care for the reproductive queen, including group defense and self-sacrifice. Haplodiploidy and Hamilton's rule All Solenopsis species has the haplodiploid sex-determination system, in which the females are developed from the merging of a sperm and an egg and the males are developed from an unfertilized egg. Ideally, according to Hamilton's rule, the female workers would all share the same father and therefore receive the same X chromosome from him and then receive one of the two possible X chromosomes from their mother, which should result in relatedness. However, because it is unknown as