Butterflies of Britain
& Europe
Peacock
Inachis io
LINNAEUS, 1758
Family - NYMPHALIDAE
subfamily -
NYMPHALINAE
Tribe - NYMPHALINI
Peacock
Inachis io, Lardon Chase, Berkshire �
Adrian Hoskins
Introduction
The Peacock is considered by many to be
the most beautiful butterfly in the world. Its beauty was remarked
upon as early as 1634 when Sir Theodore de Mayerne, physician to
King Charles 1, noted that the 'eyes' on the wings of the Peacock
butterfly "shine
curiously like stars, and do cast about them sparks of the colours
of the Rainbow".
Peacock
Inachis io, Alner's Gorse, Dorset �
Adrian Hoskins
Peacock
Inachis io, Hungerford, Berkshire �
Adrian Hoskins
The butterfly
is distributed throughout most of Europe but is absent from northern
Scandinavia, and from most of southern Spain and Portugal. Beyond
Europe its range extends across temperate Asia to Japan.
Habitats
In Britain the Peacock is a widespread
and common resident, often seen in gardens, woodlands and flowery
hillsides in late summer. The butterflies go into hibernation in
September, over-wintering in hollow tree trunks, wood stacks, farm
buildings, rabbit burrows and other locations where they can find
shelter and darkness. In early spring they awaken and can often be
often seen basking on bare earth on paths through woodland, along
lightly wooded riverbanks, disused railway cuttings, old quarries
and farmland.
Peacock
Inachis io,
Alice Holt forest, Hampshire �
Adrian Hoskins
Lifecycle
In April and May, female
Peacocks can often be seen flying around clumps of stinging nettle
Urtica dioica in woodland glades,
country lanes and farmland. They eventually settle under the upper
leaves of the nettles, where they lay their dull green spherical
eggs in large heaps.
Immediately
after hatching, the larvae spin a silken web on the upper leaves of
the nettles, and live within this during the early instars,
venturing out to feed in warm weather. They all feed and grow at
roughly the same rate. After each moult they divide into
increasingly smaller groups, each time moving on to another nearby
plant. They are conspicuous, feeding openly in groups on the upper
surface of the leaves. If molested they react by 'reflex bleeding',
i.e. they spurt a foul smelling and noxious fluid from glands behind
the head. This acts as a warning to wasps, spiders and predatory
birds that they are distasteful and should be left alone.
Molestation also causes the caterpillars to wriggle violently and
drop from their leaf into the herbage below, presumably as a defence
against parasitoid wasps or flies. Nevertheless at least 90% of
Peacock caterpillars fall victim to attack by the Tachinid fly
Zenilla vulgaris. Other Tachinids
including Pelatachina tibialis,
Sturmia bella and
Phryxe vulgaris are also recorded as parasitizing
Inachis io.
By the time they reach the final instar the larvae become solitary
in behaviour. They are handsome velvety black creatures, covered
with black spikes, and studded with tiny white tubercles.
Inachis io,
5th instar larva, Hungerford, Berkshire �
Adrian Hoskins
In some years
Peacocks breed especially successfully and the larvae can be
extremely abundant - on 5th July 2013 for example I checked a 400
metre stretch of hedgerow between 2 rape fields at Hungerford in
Berkshire and counted no less than 22 separate larval webs
comprising an estimated total of 1400 larvae, ranging from 1st to
4th instar.
The chrysalis is pale
green with a dark diagonal streak across the wing cases, and can
reputedly be found hanging from woody stems or tree trunks in the
vicinity of nettles.
Peacocks
Inachis io, Noar Hill, Hampshire �
Adrian Hoskins
Adult behaviour
Peacocks emerge in late July and throughout August, and generally
spend a few days very close to the emergence site, nectaring at
thistles, knapweeds, hemp agrimony, ragwort, marjoram and bramble
flowers.
At Noar Hill in Hampshire on 31st July 2009 there were an
exceptional number of Peacocks present, well in excess of 150, by
far the highest concentration of this species I have ever seen.
There were often 15 or 20 on a small patch of thistle or a single
clump of hemp agrimony. At about 6.30pm the breeze suddenly dropped,
and cloud cover obscured the sun. The Peacocks quickly responded by
settling in groups of up to 6 to bask on ant hills and patches of
bare chalk.
After dispersing from the 'honey pot' nectaring areas in the
countryside, the adults commonly visit gardens where they nectar at
michaelmas daisies, ice plant and buddleia. In September they return
once more to the countryside, visiting flowery hillsides where they
gorge themselves on the nectar of devil's bit scabious to prepare
themselves for the long winter ahead.
By late September they enter hibernation, usually at woodland sites,
where they spend the winter months hidden in hollow tree trunks, log
piles, farm out-buildings and other cool dark places where their
blackish mottled undersides provide them with excellent camouflage.
They re-awaken on the first sunny days of spring, sometimes as early
as January, although mid March is more typical. They are very long
lived butterflies, and there are usually a few individuals flying in
late May or early June, almost overlapping with the next generation
of adults.
Peacock Inachis io, Noar Hill,
Hampshire �
Adrian Hoskins
In spring Peacocks will use almost any available nectar source,
including blackthorn, bugle, sallow catkins, bluebell, cuckoo
flower, ground ivy, daisies, wood anemone and dandelion.
During April, at around midday, males establish small territories on
the ground, typically choosing sunny sheltered spots close to
hedgerows or woodland edges, or along woodland rides. Often as many
as a dozen males will set up their territories close together along
a woodland track, and each will instantly fly up to chase after any
passing bee, fly or butterfly. In April 2006 I watched 2 males that
had set up territories about 5 metres apart, along a ride in
Stansted Forest. One male had been chasing after a Comma, and
encroached into the territory of the other male Peacock. A sortie
then took place, with both males spiralling rapidly to a height of
about 20 metres before separating and returning to their original
territories. On another occasion I watched a male Comma defending
its territory against a Peacock. Despite the greater size of the
Peacock, which repeatedly attempted to occupy the territory, it was
successfully ousted by the Comma.
In
April 2007 at Botley Wood I watched a sortie between a male Comma
and a male Peacock both of who believed they had 'ownership' of a
particular birch log. The pair engaged in battle dozens of times
during a 20 minute period but eventually the Peacock was driven off,
leaving the Comma to occupy the territory.
When
female Peacocks pass through the male territories they are instantly
intercepted and pursued at high speed. Often the chasing male will
inadvertently fly into the dominion of another male, and a
territorial battle will take place during which the female will
escape. Despite the abundance of the butterfly, neither myself, or
as far as I am aware anyone else, has observed the courtship or
found a copulated pair.
Peacock
Inachis io, Hungerford, Berkshire �
Adrian Hoskins
Peacocks
often close their wings when settled, but if disturbed suddenly
re-open them, producing a rasping or hissing sound created by
rubbing the veins on the forewings and hindwings together. The
sudden appearance of the 'peacock eyes' probably functions to
startle attacking birds. The effect is short-lived however and
having recovered its senses the bird may still attack. The 'eyes'
then serve to divert the attack away from the butterfly's vulnerable
body and onto the outer part of the wings. Butterflies are usually
still able to fly well, even with large chunks pecked out of their
wings. It is thought that the hissing noise is a defence against
bats which may disturb the butterflies when they enter caves or
hollow tree trunks to roost or hibernate.
In a study by
Stockholm University, the ocelli of several Peacocks were blanked
out with a marker pen. When exposed to blue tits, 13 out of 20 were
attacked and eaten. A control group of Peacocks with the ocelli
intact fared much better, with only a single butterfly attacked out
of a group of 34. It can be concluded that in 97% of encounters with
blue tits, the ocelli are effective as a deterrent, and the
butterfly will escape unharmed. A project carried out by another
biologist found that normally marked Peacocks escaped attacks by
yellow buntings 76% more often than Peacocks that had their eyespots
painted out.
Peacock
Inachis io, Alner's Gorse, Dorset �
Adrian Hoskins
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