European Peacock

They are more commonly known as the peacock butterfly. The butterfly has a wingspan of 50 to 55 mm. The base colour of the wings is a rusty red, and at each wingtip, it bears a distinctive, black, blue and yellow eyespot. The underside is a cryptically coloured dark brown or black. There are two subspecies: one is found in Azerbaijan, and the other is found in Japan and the Russian Far East.

Habitat

The peacock butterfly occurs in temperate regions of Europe and Asia, with a range that extends from Britain and Ireland eastwards through Russia to eastern Siberia, the Korean peninsula and Japan. It is absent from northern Scandinavia and southern parts of Spain and Portugal. It also occurs in temperate regions of Turkey and northern Iran and has been recorded at elevations of up to 2,500 metres. It is sometimes known as the European peacock, to distinguish it from another butterfly, from a completely different family, that occurs in North America.

Distribution in Scotland

Prior to the end of the 20th century, the peacock butterfly was only known from some parts of Scotland, having been recorded in less than 30% of the country. However, since then it has spread rapidly and is now seen in most of the Scottish mainland and many of the islands, including the Outer Hebrides, Orkney and Shetland. While the reasons for this expansion of its range are not fully understood, one possible explanation is the recent warmer weather, due to human-caused global warming.

Diet

Adult peacock butterflies emerge from the middle of July onwards and feed on the nectar of summer-flowering plants such as thistles, ragwort and devil's-bit scabious, as well as sap and honeydew. They also visit various garden flowers and will feed on rotten fruit, through into early autumn. While doing so, they build up reserves of body fats in preparation for hibernation during the winter. Hibernation sites can be hollow trees, piles of deadwood, or buildings such as sheds and barns, and the butterfly will remain there for seven or eight months until the following spring.

Breeding

The peacock butterfly overwinters as an adult, and in early spring it emerges from hibernation to reproduce. During this time it feeds on the nectar of spring-flowering plants, such as primrose and bluebells. After mating, up to 500 eggs that are green with white stripes on them are laid by the female. She chooses a stinging nettle, which is the main food plant for the larvae, for this and lays the eggs on the underside of the leaves of a plant that is growing in full sun. The eggs hatch after about 10 days, during the period from late May until early July, and the larvae spin a communal 'tent' or web of silk near the top of the nettle plant, which provides some protection from predators. The larvae feed inside the tent until the food supply is exhausted, and then move to a different part of the plant, where another tent is spun. As the larvae grow, they emerge to feed collectively and then separately, and go through 5 stages of growth or development called instars, which are separated by moults, when the skin they have outgrown is shed. The larvae or caterpillars are dark in colour and covered in spines, and by the fifth or final instar, they are up to 4.2 cm long, jet black in colour, with white spots and formidable-looking black spikes.

When it is fully grown, the caterpillar finds a suitable place to pupate, which can be either on the underside of a nettle leaf or on the stem of a plant. The chrysalis or pupa is formed by the caterpillar spinning a protective cocoon around itself and is either pale yellow-green or grey in colour. The former provides camouflage when the chrysalis is attached to a leaf, while the latter colour serves the same function when the pupation site is a plant stem or tree bark. The chrysalis is suspended head-down, as the caterpillar uses its rear legs to hold on to the leaf or stem.

Inside the chrysalis, the process of complete metamorphosis takes place, whereby the caterpillar body breaks down into a 'chemical soup'. From this, the adult butterfly begins to take shape, with its structures and organs developing from small groups of special cells known as germinal buds. When this development is complete, after twelve days or two weeks, the adult breaks out of the chrysalis. The newly-emerged butterfly then finds a place to perch, so that it can expand its wings by pumping blood into the veins they contain. After one or two hours the wings are sufficiently stiff and the butterfly is ready for its airborne adult life.

Population

They have not been assessed on the IUCN Red List but there is a widespread amount of individuals but the number of mature individuals are unknown.

Threats

The peacock butterfly suffers from a number of parasites. These include a parasitoid wasp that lays its eggs on the young caterpillars, which subsequently die as the wasp's own larvae grow within them. Two parasitoid flies also cause mortality in the larvae in a similar fashion. Two entomopathogenic (ie insect-killing) fungi have been recorded as affecting peacock butterflies hibernating in underground shelters in Europe. Predators of the peacock butterfly include various spiders, which attack the caterpillars, undeterred by the spines. Wood mice will eat hibernating adults if they find them, and birds such as the blue tit, great tit and yellowhammer will attack the adults when they are out in the open.

Conservation

Butterfly Conservation priority: Low
European status: Not threatened