Papilio polyxenes

Papilio polyxenes, the (eastern) black swallowtail, American swallowtail or parsnip swallowtail, is a butterfly found throughout much of North America. It is the state butterfly of Oklahoma and New Jersey. An extremely similar-appearing species, Papilio joanae, occurs in the Ozark Mountains region, but it appears to be closely related to Papilio machaon, rather than P. polyxenes. The species is named after the figure in Greek mythology, Polyxena (pron.: /pəˈlɪksɨnə/; Greek: Πολυξένη), who was the youngest daughter of King Priam of Troy. Its caterpillar is called the parsley worm because the caterpillar feeds on parsley. The Papilio polyxenes demonstrates polyandry and a lek mating system, showing no male parental care and display sites. Females are therefore able to choose males based on these sites and males are the only resource the females find at these sites. P. polyxenes is part of the tribe Papilionini of the swallowtail butterfly family, Papilionidae. The members of this tribe all have tails on the hindwings, and therefore include species named swallowtail. P. polyxenes is part of the genus Papilio, which is the biggest group of the family Papilionidae. Members of this genus typically feed on plants of the family Lauraceae, Rutaceae and Umbelliferae. Papilio polyxenes are found from southern Canada through to South America. In North America they are more common east of the Rocky Mountains. They are usually found in open areas like fields, parks, marshes or deserts, and they prefer tropical or temperate habitats. Eggs are pale yellow. Young larvae are mostly black and white with a saddle, and older larvae are green with black transverse bands containing yellow spots. This caterpillar absorbs toxins from the host plants, and therefore tastes poor to bird predators. The black swallowtail caterpillar has an orange 'forked gland', called the osmeterium. When in danger, the osmeterium, which looks like a snake's tongue, everts and releases a foul smell to repel predators. The pupae may be green or brown, but not depending on surroundings or the background on which they have pupated. The color of the chrysalis is determined by a local genetic balance that ensures the majority of pupae will blend in. A section of the green pupae will turn a much darker green at the very end of the pupae stage. This color change occurs a few hours to a full day before hatching. Unusually, this butterfly's chrysalis is girdled with a loop, with its feet attached to the silk pad, which helps the butterfly to unfold its very large wings when crawling out. The black swallowtail has a wingspan of 6.9–8.4 cm, and females are typically larger than males. The upper wing surface is black with two rows of yellow spots – these spots are large and bright in males and smaller and lighter in females. Females have a prominent blue area between these two rows, while males have a much less prominent blue area. These differences give rise to effective Batesian mimicry seen in females.