Imperial Moth

Eacles imperialis — the imperial moth — is one of the largest and most striking giant silk moths in eastern North America and one of the most widespread Saturniidae on the continent. The species is found across all of eastern North America from southern Canada south through the eastern US to northern Argentina (an unusually broad range for a Saturniidae giant silk moth). Adults are 8-17 cm wingspan (the variation is enormous — northern individuals are 8-10 cm, southern individuals can reach 14-17 cm), with brilliant YELLOW WING COLORATION marked by patches of pink, purple, brown, and red that resemble a burst of autumn-colored maple leaves scattered across each wing. The combination of bright yellow ground color and warm sunset-colored markings makes the species one of the most dramatically beautiful Saturniidae in North America. The species is sexually dimorphic in coloration: males have darker, more pink-and-purple-marked wings; females have lighter, more yellow-dominated wings with smaller markings. Adults are nocturnal, do not feed (the digestive system is non-functional — they live 1-2 weeks on stored larval body fat), and females release pheromones to attract males. Larvae are equally striking: 10-12 cm long, bright green to brown to black (variable across individuals — the larvae are color-polymorphic), with bright orange-and-cream stripes along the body and FOUR PROMINENT DORSAL HORNS on the thoracic segments (unlike the regal moth larvae's head horns, the imperial larvae's horns are on the back). Larvae feed on a remarkably wide range of host plants — over 50 species of trees and shrubs are recorded as imperial moth host plants, including pine, oak, maple, sweetgum, sassafras, birch, sycamore, and others. The exceptionally broad host range is one of the species' major ecological features and is unusual among giant silk moths (most of which are restricted to specific host plant families). Pupation occurs in shallow underground chambers — unlike most Saturniidae which spin elaborate silk cocoons above ground, imperial moth larvae burrow into soil and pupate underground without a silk cocoon. The species is one of the most-photographed giant silk moths in eastern North American macro nature photography because of the dramatic wing coloration. Adults are commonly attracted to porch lights and other artificial lights in late summer. The species is harmless to humans.