When observing the colourful wings of the butterfly Aglais io as it sips nectar from buddleia in the garden or from a variety of meadow and woodland flowers, it is easy to understand why it is called the ‘Peacock’. The arrangement of scales on the upper surface of the wings to give the impression of ‘eyes’ has been the subject of much speculation, with one hypothesis suggesting that the eyespots act as a defence mechanism by scaring avian predators by mimicking the eyes of the birds’ own potential predators, and another hypothesis being that the eyespots may direct any attack to the periphery of the wings rather than towards the head and body of the butterfly.
When hibernating on the ground however, with the wings closed and only the mottled brown underside of the wings exposed, they become camouflaged amongst the dead leaves. It is during these dark winter months when the Peacock butterfly could still be at risk from small rodent predators, and any startling visual display of eyespots would be ineffective. Studies have indicated, however, that mice can be deterred by the hissing noise and ultrasonic clicks made when the butterfly rubs its wings together.
Peacock butterflies awake from hibernation with the onset of warmer weather in the spring. Following mating, the female lays clusters of eggs on the underside of leaves of the common nettle (Urtica dioica), On hatching, the larvae (caterpillars) spin a web around leaves and will live and feed within that web – moving to a new plant when the leaves are consumed. After about a month, each larva forms a pupa (chrysalis) before developing into an adult a few weeks later.
