Peacock Aglais io (Linnaeus 1758)

Family: Nymphalidae, subgroup Nymphalinae (The Nymphalids or Vanessids)


Header photo by Emma Walters

Photo above left by Trevor Baker

Photo above right by Lauren Teate

The Peacock is a large red butterfly which can’t be confused with any other species. The most obvious feature are large bluish “eyes” on each wing. By flicking its wings open the eyes make the butterfly look a bit like an owl and this might startle predators. The underside is a very dark mottled brown which is almost black, so the butterfly can be hard to see when it’s resting with its wings closed. When flying above it seems black and often looks larger than it actually is.

The sexes are virtually identical, but females are usually larger. Peacocks are unusual in that they sometimes fly at night and get caught in moth traps.


The Peacock is a very mobile species that appears anywhere, from city centres to forest rides, moorland valleys, coastal cliffs, and dunes. It particularly likes open woodland areas and is well-known as a garden butterfly where it nectars on a wide range of flowers, especially buddleia. Females usually lay their eggs on common nettles Urtica dioica, preferring nettles in full sun, but sheltered by trees or shrubs.

Adults usually emerge from hibernation March to May and nectar on dandelions, willow catkins and hawthorn blossom.

Many Peacocks are not properly resident on any given site. They constantly wander, heading northward in spring and early summer and flying about half a kilometre per day, with males holding different territories along the way. This implies that there is regular immigration into the county from the south and emigration to the north. The degree to which there is any immigration from the continent is unclear, due to difficulties in knowing where individuals are going from and to. Movements reverse around mid-Aug with a drift towards the south and south-east.


The Peacock is common and widespread throughout Yorkshire except for the high Pennines, though it appears to be moving into higher areas. The largest counts are in the south and south east areas of Yorkshire. Peacocks became rare in Yorkshire in the early part of the last century and didn’t start to appear again until around 1960. From the late eighties it gradually became very common and is probably more widespread now than it has been for over 150 years.

Numbers fluctuate a large amount from year to year throughout Britain and it is usually absent from north Scotland. However the species is currently expanding its range.

Peacocks are resident from north Spain up to south Norway and Finland, and eastward through temperate Asia to Japan. They live in areas up to 2500 metres.

Life Cycle

There is usually one brood (late July to early September) which hibernates and re-appears the following March to May, with a few stragglers still flying into early July. However it is recorded in every month of the year due to hibernating individuals waking up in winter as a result of disturbance or warmer weather.

Springtime males can often be seen spiralling high in the air in territorial arguments. A male may suddenly leave a territory to follow a female across the countryside until she chooses a roosting site (probably high in a tree), where mating takes place, under cover of darkness and unseen (and as far as we know un-photographed!).

Once mated, females continue journeying, trying hard to shake off any pursuing males. Clusters of 300 to 500 eggs are laid on the undersides of nettle leaves, usually around the middle of the day. Greenish-grey larvae hatch one to three weeks later and develop through five instars into conspicuous hairy black larvae, speckled with white dots, in June and July. They feed inside communal webs, periodically re-built on fresh nettle stems.

Larvae usually pupate on nearby shrubs or tree trunks and the pupae are well hidden, hanging from silk pads for two to four weeks before hatching. Summer emergence in Yorkshire is typically between late 20 July and 8 August, depending on weather conditions and butterflies sometimes hibernate after only a few days. By late August or early September they become less active as they look for somewhere to hide; e.g., tree holes, sheds, garages or even churches. Roosting or hibernating Peacocks may react to disturbance by flicking their wings to show their eye like pattern. At the same time they can produce a creaking sound by rubbing their wings together and a communal roost reacting together can produce a hissing sound like a snake! The eye patterns not only serve to frighten potential predators, but may also direct any attack at the wings rather than the body. Hence the summer sight of Peacocks with bites out of their wings, but still flying.


The species is not under threat.


There are over 40 named aberrations including a 'blind' variety lacking blue eye marks (ab belisaria Oberthur), and one giving an impression of transparent wings, (ab transparens Beuret).

With thanks to the Butterflies of Yorkshire edited by Howard M Frost

Catherine Jones 15/01/21