The slutterfly, Synchlora copula, is, in fact, not a butterfly, but a moth. Although the phylogeny of the Lepidoptera is not without arguments, the difference between moths and butterflies is generally accepted. Moths are mostly night active (although there are some exceptions), and their antenna are much more developed than those of butterflies. So it is, too, with the slutterfly.
The species is believed to have evolved ten million years ago in tropical Africa, long before the apparition of modern man. Like most moths, the pheromones emitted by females attract the males, who can trace even single particles of a potential sexual partner's scent. But due to the vast geographical distribution and the number of related species, the slutterfly has developed a means of reinforcing this signal beyond what normal moths are capable of.
All animals, not only moths, use pheromones to convey information to other members of their species, be it fear, sexual readiness, or genetic information. Given the less sensitive nature of their sensory organ when it comes to airborne particles, most mammals emit a huge amount of pheromones, at least in comparison with insects. Slutterflies use this to their advantage.
The female slutterfly lies its eggs in the small of the back of passing female mammals, just underneath the skin. These eggs, in turn, hijack the mammals pheromone-machinery, adding a subtle twist to them, which is recognized by male slutterflies. The males are attracted by the scent, and fertilize the eggs. Once said eggs mature, the detach fro their host, and the muscle movements used during fecal excretion push them out of the skin, causing them to land in proximity of the dung that will serve as nourishment for the larva. In case the eggs are not fertilized within a certain time of their laying, they will undergo parthenogenesis, and develop all the same, although with lower genetic variance.
However, the hijacking of the hormonal machine in its host is not without consequence. Animals that have been visited by a female slutterfly have a higher rate of fertility, and the species has long been considered an omen of good fortune in African tribes. Young woman would paint them in the small of their back as a sign of procreative availability. In some tribes, they mating cycle of the slutterfly would influence that of the tribe itself. Those woman who had been visited by a slutterfly would be considered especially valuable for procreation, and only the best hunters of the tribe where considered for mating by those women.
In recent years, this ancient sign of fertility has been popularized in western culture, although the ancestral meaning of fertility and procreation has been lost. Seen as a pure symbol of sexual availability, the slutterfly tattoo has given its vernacular name to Synchlora copula in a strange twist of anachronic irony. And what once was a symbol of family and high standing within society, has now become a means to indicate absence of procreation and easy pickings for sexual intercourse.