Papilio multicaudata

Papilio multicaudata, the two-tailed swallowtail, is a large butterfly of the family Papilionidae found in western North America, from southern Canada through the western United States and Mexico to Guatemala. Its wings are yellow with black tiger striping and several blue markings on each hindwing, and most individuals have two tails on each hindwing and a small orange eyespot near the lower angle, which can lead predators to strike the rear of the butterfly instead of its head. With a wingspan of roughly three to six and a half inches it is the largest swallowtail in western North America, and females are larger, more brightly coloured and more blue-marked than males. It typically lives near streams and in moist valleys, but also occurs in canyons and in cities at lower elevations. Caterpillars feed on host plants such as chokecherry, hoptree, ash and Arizona sycamore, there is one brood a year, and the pupae overwinter. Three subspecies are recognised, and the butterfly is the state butterfly of Arizona.