Peacock butterfly

The peacock (bird) is unmistakable thanks to the “eyes” that are visible when the male bird displays its tail as part of its mating display. The peacock butterfly is similarly unmistakable, although the “eyes” have a different function, namely to frighten off predators when the butterfly opens its wings.

The peacock (Inachis io) is native to Europe and Asia, preferring the temperate regions that exclude both the far north and the hotter southern countries of Asia. It is non-migratory and many individuals are able to hibernate during the winter in lofts, cellars, caves and other sheltered places. It can be seen in flight in Great Britain between July and October (new brood) and in spring (over-winterers). 

The peacock is a medium to large butterfly, with a wingspan of 5.4 to 6.0 centimetres (2.1 to 2.4 inches). Females are slightly larger than males. 

The colouring of the upper wings is dark reddish-brown with yellow and black markings. There is an “eye” on the apex of each forewing and hindwing. The forewing eyes have brown centres with yellow and blue surrounds. Small white “tears” appear to be being shed from the outer corners of the eyes.  The eyes on the hindwings are blue with black surrounds. The undersides of the wings are almost black, which adds to the shock effect when the peacock suddenly opens its wings as danger approaches. Males and females have similar markings.

The food plant of the caterpillars is the stinging nettle, which is found in abundance in both rural and urban locations, and at altitudes from sea level to mountainsides. Butterflies take nectar from many varieties of flowering plant and are frequent visitors to buddleia plants (the “butterfly bush”) in parks and gardens. These facts mean that the peacock can be seen virtually anywhere within its geographical range, and is very common.

Eggs are laid in batches on the underside of nettle leaves. After about a week the caterpillars hatch and crawl to the top of the plant where they spin a communal nest and live as a group. The caterpillars, which are black and spiky, separate when approaching full growth, which takes about two or three weeks. They will often wander some distance from the food plant before pupating, and the pupa can be either grey or yellowish-green. The pupal stage takes about 10 to 14 days to complete before the adult butterfly emerges.

© John Welford