Peacock butterfly (Insects) by Adam Swaine Via Flickr: Aglais io, the European peacock, more commonly known simply as the peacock butterfly, is a colourful butterfly, found in Europe and temperate Asia as far east as Japan. It was formerly classified as the only member of the genus Inachis..The Peacock’s spectacular pattern of eyespots evolved to startle or confuse predators, make it one of the most easily recognized and best-known species