Peacock Butterfly

Aglais io — the peacock butterfly — is one of the most familiar and most spectacular butterflies in Europe and one of the most theatrical defensive displays in the entire European Lepidoptera. The species is widespread across Europe, North Africa, and into central and eastern Asia. Adults reach 5-6 cm wingspan. The species' defining feature is the wing pattern: brilliant rust-red upperside carrying FOUR enormous concentric eye-spots — one near each wing tip. Each eye-spot is composed of concentric rings of red, blue, gold, and black, and the four eyes together create a striking impression of a small vertebrate face peering out of the foliage. Wing undersides are dramatically different — dark mottled brown that perfectly mimics dead leaves and bark when the wings are folded at rest. The species is the textbook example of dual-sided defensive coloration in butterflies (cryptic underside, dramatic flash upperside). The species also possesses one of the few audible-sound defensive displays in adult butterflies: when threatened, the peacock rapidly opens her wings (revealing the eye-spots) AND simultaneously rubs specialized wing veins together to produce an audible hissing sound. The hissing is generated by friction between corresponding patches of modified wing-vein scales on the forewing and hindwing as the wings move. The combined visual flash + audible hiss display reliably startles approaching small-mammal and bird predators (Olofsson et al., 2012, Behavioral Ecology, demonstrated that European blue tits flinch and reject perched peacock butterflies that perform the display). The species overwinters as adults in tree hollows, woodpiles, and outbuildings; one of the few European butterflies that remains active during occasional warm winter days. Caterpillars are dramatic: bright black with white spots and white-base spines, feeding gregariously on stinging nettle (Urtica dioica) in spring and early summer.