Butterflies of
Britain & Europe
Peacock
Inachis io
LINNAEUS, 1758
Family - NYMPHALIDAE
subfamily -
NYMPHALINAE
Tribe - NYMPHALINI
introduction
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habitats |
lifecycle |
adult behaviour
Peacock
Inachis io, Alner's Gorse, Dorset
Introduction
The Peacock is justifiably considered by many to
be the most beautiful butterfly in the world.
It's 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".
The
butterfly
is distributed throughout most of Europe, but absent from
northern Scandinavia, and from most of southern Spain and
Portugal. Beyond Europe it's range extends across temperate Asia
to Japan.
The butterflies
are fairly nomadic in behaviour, and can be found in almost any
sheltered habitat in England and Wales. In Scotland and Ireland
the butterfly has generally been regarded as scarce, but there
is evidence that it is spreading further north in response to
global warming, with a few records even from the Outer Hebrides.
Peacock
Inachis io, Stockbridge Down, Hampshire
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
initially
to startle attacking birds.
The
effect is short-lived however, and having recovered
it's 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
can continue to fly normally, 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.
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,
rock-crevices and other locations
where they can find shelter and darkness.
In early spring they awaken, and are often seen basking on bare
earth on paths
through woodland, along lightly wooded riverbanks, disused railway
cuttings, old quarries and farmland.
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Peacock
Inachis io, Alice Holt forest, Hampshire |
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.
The
larvae all feed and grow at roughly the same rate, and moult in
synchrony. After each moult they split into increasingly
smaller groups, each time moving on to another nearby nettle
plant. They are very conspicuous, feeding openly in groups on
the upper surface of the leaves.
If they are disturbed, the entire mass of larvae wriggle violently,
presumably as a defence against parasitoid wasps or flies.
Nevertheless over 90% of larvae are said to succumb 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 it reaches the final instar the larva is solitary in behaviour.
It is a handsome velvety black creature,
covered with black spikes, and studded with tiny white
tubercles.
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.
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Peacocks
Inachis io, Noar Hill, Hampshire |
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 at the same time 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, and made a wonderful sight.
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 ( e.g. I watched a Peacock basking on a rock in Stansted
Forest on 26th January 2008 ),
but
early-mid March is more typical. They are very long lived
butterflies, and there are usually a few individuals flying in
late May or even at the beginning of June, almost overlapping
with the next generation of adults.
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Peacock
Inachis io, Noar Hill, Hampshire |
In spring Peacocks will use almost any available nectar source,
including blackthorn, bugle, bluebell, cuckoo flower, sallow
catkins,
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,
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 Comma defending it's
own
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.
At Botley Wood in April 2007, I
watched an aerial battle 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 many 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, Alner's Gorse, Dorset
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