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Butterflies of
Britain & Europe
Grizzled Skipper
Pyrgus malvae
LINNAEUS, 1758
Family - HESPERIIDAE
subfamily -
PYRGINAE
Tribe - PYRGINI
introduction
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habitats |
lifecycle |
adult behaviour
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Grizzled Skipper
Pyrgus malvae, male,
Stockbridge Down, Hampshire |
Introduction
The
Grizzled Skipper flies very rapidly, usually very close to the ground, and is
extremely difficult to follow in flight. As a result of it's small size, rapid and erratic
flight pattern, and lack of bright colours it is easily overlooked and
certainly
under-recorded. Transect analysis however provides evidence of the butterfly's
decline in the UK, where it is now regarded as a localised and fairly scarce
species.
It
is distributed throughout most of Europe but absent from Scotland, Ireland,
northern Scandinavia and most Mediterranean islands. Beyond Europe it occurs
from northern Turkey, across temperate Asia to northern China and Korea.
Confusingly the butterfly has
undergone several name changes, being originally known as the Marsh Fritillary,
a name that is now applied to a totally different insect in the Nymphalidae !
Other former names include "Mr Dandridge's Dark Fritillary", "Spotted Skipper"
and "the Grizzle".
The
sexes can be distinguished easily - males have a fold along the leading edge of
the forewings. This fold contains androconia which release pheromones. Over a
period of several days these become exhausted. Females are able to assess the
age and virility of the males by "reading" the strength of the remaining
pheromones.
Both sexes are
prone to variation in the size and extent of the white markings. The ground
colour is deep black when the butterflies are freshly emerged, but quickly fades
to a dark earthy brown. At a few sites a recessive gene causes the periodic
appearance of an aberrant form known as taras, in
which the white markings on the forewings are greatly elongated and enlarged.
The
Grizzled Skipper
cannot be mistaken for any other species in Britain, but there are a large number of
very similar Pyrgus, Spialia
and Muschampia
species found in other parts of it's range with which it can very easily be confused.
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Grizzled Skipper
Pyrgus malvae, male,
Stockbridge Down, Hampshire |
Habitats
In Britain
this species is widespread throughout central and southern counties, but it's
range has contracted dramatically in recent years. It is now very localised, but
can still be found in reasonable numbers
on many
chalk grassland sites; and small colonies persist in certain woodlands, where
it breeds in clearings, and along the edges of sunny forest tracks. Other
habitats include scree slopes,
railway
cuttings and embankments,
abandoned quarries, spoil heaps and
limestone
pavements.
Grizzled Skipper
sites are always in sheltered sunny situations, and are characterised by having
substantial areas of broken ground in the form of rabbit scrapes, eroded banks,
or disturbed ground. These bare areas encourage germination of the larval
foodplants, and provide the warm microclimate which is essential to the
butterfly.
Grizzled Skipper
Pyrgus malvae, male, Magdalen Hill Down, Hampshire
Lifecycle
The
flight season is greatly affected by climatic conditions
in early spring. In forward seasons the butterflies can appear in
early April, but they may not emerge until May in a late
season. Numbers tend to build up gradually throughout May, and in
late seasons the butterfly can often still be found in mid-June. In
Europe there is a partial 2nd brood emerging in August, but
records of a 2nd brood in Britain are extremely rare.
The greenish white dome-shaped eggs are laid
singly in April and May on the undersides of leaves of wild
strawberry
Fragaria vesca, creeping
cinquefoil
Potentilla repens,
tormentil
P. erecta, or agrimony
Agrimonia eupatoria. More rarely
young suckers of bramble Rubus fruticosus
may be used. The eggs hatch after about 10 days.
When small, the caterpillar is
yellowish, and rests
under a thin veil of silk spun over the midrib on the upper
surface of leaves. It produces characteristic blotches nibbled
out of the upper cuticle. When older it lives within a folded
leaf spun together with a few strands of silk. The fully grown
larva is green with narrow brown stripes along the back and
sides.
Pupation takes place in August.
The pupa is formed within a thin net-like cocoon spun near the base
of the foodplant. It is very distinctive, with the abdomen and
thorax dark brown, and the wing cases greenish white. The pupal
stage lasts from August until the following April or May.
Adult behaviour
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Grizzled Skipper
Pyrgus malvae, male perching on
ribwort plantain |
The butterflies are extremely active, usually seen zigzagging or buzzing in
tight circles just above the surface of the ground, but they
seldom fly more than a few metres from their emergence site.
They are very difficult to follow with the eye, and in flight can
very easily be mistaken for large flies.
Grizzled Skippers are usually seen in small groups, with 2 or 3
males having overlapping territories, typically in sheltered
pockets at the bottom of hillsides. Each male perches on it's
own particular leaf or stone - a lookout post from which it will
instantly dart up to challenge any fly, bee or butterfly that
comes within range. When 2 males meet, they spiral rapidly
together to a height of about 2 metres, after which each male
returns to it's original perching place.
Courtship is very brief. When a
male intercepts a female, he flies close behind her until she
settles on the ground. He then lands next to her, buzzing
excitedly around her during which time she is able to assess his
virility by evaluating the strength of his pheromones. If the
female is receptive she raises her wings, allowing the male to
move
alongside her. The male then curves his abdomen around to make sexual contact.
The pair then adjust position to face away from each other, and
bask with their wings almost fully outspread.
Copulation takes place in
the late morning, and lasts for about an hour.
Favourite nectar sources of the Grizzled Skipper include bird's
foot trefoil,
bugle, ground ivy, daisies, buttercups,
violets, hawkbit and dandelions.
In
overcast but warm weather the butterflies often bask on
bare soil, stones
or
low herbage,
but in sunny conditions they prefer to bask on grass-heads.
In late afternoon they
go to
roost
on
dead
flower-heads,
particularly
favouring St
John's
wort and
marjoram, but will also roost on grass heads or at the tips of
bramble sprigs.
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Grizzled Skipper
Pyrgus malvae, female roosting on
St John's wort, Magdalen Hill Down, Hampshire |
Grizzled Skipper
Pyrgus malvae, female roosting on
dandelion, Magdalen Hill Down, Hampshire
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