Butterflies of
Britain & Europe
Chequered Skipper
Carterocephalus
palaemon
PALLAS, 1771
Family - HESPERIIDAE
subfamily -
HETEROPTERINAE
introduction
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habitats |
lifecycle |
adult behaviour
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Carterocephalus palaemon, Szalafo-pityerszer, Orseg,
Hungary
( image ©
Peter Bruce-Jones ) |
Introduction
The
Chequered Skipper is distributed across much of central and northern Europe,
although absent from
Spain, Portugal, peninsular Italy and the Mediterranean
coast. Beyond Europe it occurs across much of temperate Asia, reaching
Japan. It also occurs
across the Hudsonian zone of Canada, and in the Rocky mountains of the USA,
where it is known as the Arctic Skipperling.
Older literature works treat this species as a member of the Hesperiinae, but it is
currently placed in the Heteropterinae due to differences in the
structure of the antennae, palpi and venation. There are only a few members of
the Heteropterinae that occur in the northern hemisphere. In South America there
are many related species in the genus
Dalla
- largely montane species from the Andes; and another similar genus, Metisella,
occurs in the tropics of Africa.
The
only European species with which
palaemon
can be confused is the Northern Chequered Skipper
Carterocephalus silvicolus,
which has a similar underside, but the yellow spots on the
upperside are larger and merge together. The latter species is found in north
Germany, Poland, and in sub-arctic regions from Scandinavia to Siberia, Amurland
and northern Japan. It does not occur in Britain.
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Carterocephalus palaemon,
Kercaszomor,
Hungary
( image ©
Peter Bruce-Jones ) |
Habitats
In England the Chequered
Skipper
was once quite widespread, occurring across most of the central and eastern
counties,
but it contracted it's range, partly as a consequence of drainage of the Great
Fen, which led to the large scale conversion of land to agriculture. By the early 20th century the species was thought to be confined to a few counties in the
east Midlands, and although it remained fairly common in certain areas until the
early 1960's, within a decade populations at all its English sites had
collapsed, and by 1975-76 it had become extinct. Reintroduction trials have
taken place since 1990 with varying degrees of success.
The butterfly's existence
in Scotland was not known until 1942 when it was discovered by a collector, Mackworth-Praed, in Western Inverness-shire in Scotland.
The butterfly had in fact been known from another nearby locality for 3 years
previously, having been found by Evans, but that site was a well kept secret.
In 1982 I surveyed the Highlands for this species, and found it widespread,
discovering 14 colonies including 4 that were previously unknown. Since that
time further studies have been carried out by Butterfly Conservation, and it is
estimated that the butterfly currently ( 2009 ) breeds in about 10 core areas.
Within that total area there are about 40 discrete colonies.
In
Scotland the butterfly is found at warm, sheltered, damp sites where the
larval foodplant, purple moor grass
Molinea caerulea
grows in lightly wooded areas, often in the vicinity of small streams. Examples include open oak woods, lightly wooded
gullies on hillsides and mountains, sunny glades in birch woodland, young
conifer plantations, damp scrubby areas on northern and eastern shores of
Lochs, sheltered woodland clearings, and roadside verges in wooded areas. Most
colonies occur at altitudes between sea level and about 200m. Colonies vary
considerably in size, some comprising no more than a couple of dozen insects
breeding in a woodland glade, while others may comprise of several hundred
butterflies spread over a 5 mile stretch of lightly wooded valley bottom.
In
mainland Europe the Chequered Skipper occurs at higher altitudes, between about
100-1600m, and it is far less fussy about its habitats, although it occurs primarily in damp, sunny glades and clearings in woodland, on
acidic or calcareous soils.
Climate change is likely to cause
local extinctions in more southern localities, but the butterfly may
successfully colonise new areas further north e.g. in Scotland and Fennoscandia.
Existing colonies in Scotland and the Alps will probably be forced to move to
higher altitudes as the lowlands become too warm to support the butterfly and
its habitat.
Lifecycle
In Scotland the butterflies emerge in late May and fly until mid
June.
The shiny white spherical
eggs are laid singly on the underside of grass blades.
Oviposition occurs primarily on grasses growing in
dappled sunlight beneath bog myrtle bushes. They are
usually laid on
Molinea caerulea,
but occasionally on
Brachypodium sylvaticum,
which was the grass used by the species at it's former English
sites. A much wider range of grasses are used in Europe and
North America.
The caterpillar makes it's first
meal of the eggshell. It later constructs a shelter made by
rolling a blade of grass into a tube, held together with strands
of silk. As it grows, it moves to other grass blades and
constructs larger tubes. It feeds diurnally, eating little
notches out of the grass blade above and below where it rests.
Like other grass-feeding skippers,
the larva is equipped with a pair of prongs at the tail end,
which it uses to flick away it's droppings. This helps
to prevent the grass shelter from becoming fouled, and also
removes evidence of the larva's whereabouts, which might
otherwise attract parasitoids or predators.
In late September, when the larva
is fully grown, it constructs a silken tent amongst the grass
blades, where it hibernates until April. The mature larva is
pale green, but during the autumn the colour gradually changes
to pale straw, matching the surroundings.
Prior to pupation in early May, the larva
constructs yet another shelter, made from dead grasses and silk.
The long thin chrysalis is formed within the shelter. It is pale
ochreous, marked with dark lines along the back and sides. The
pupal stage lasts for about 2 weeks.
Adult behaviour
On sunny mornings males
establish perches at a height of about 1 metre on bushes. They use
these vantage points to survey passing females, and defend the
perches vigorously against all passing insects. Other
male Chequered Skippers are promptly ousted from the vicinity.
When a female is intercepted she is chased until she settles,
whereupon copulation takes place immediately. The pair remain
joined for about an hour, during which time they sit with wings
held erect, on grass blades or other low foliage.
Both sexes spend long periods
basking on the terminal leaves of shoots of bog myrtle, birch, and
other small trees or shrubs. Unlike Hesperiine skippers, but like
the Pyrginae, they usually bask with their wings spread flat,
usually with the forewings draped slightly backwards.
They nectar, with wings closed,
at
dandelion and bugle, but also visit marsh lousewort, bluebells,
and orchids. In Scotland, and in the French Alps, I have
often found them mud-puddling, always singly, at ditches or
wet soil.
In dull dry weather and
overnight, the butterflies roost on the terminal leaves of small
bog myrtle bushes, or sometimes on bracken fronds or clumps of
heather.
In wet weather they hide themselves deep within grass tussocks.
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