Butterflies of
Britain & Europe
Marbled White
Melanargia galathea
LINNAEUS, 1758
Family - NYMPHALIDAE
subfamily -
SATYRINAE
Tribe - SATYRINI
subtribe - MELANARGIINA
introduction
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habitats |
lifecycle |
adult behaviour
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Marbled White
Melanargia galathea,
copulating pair,
Lulworth Cove, Dorset |
Introduction
A freshly emerged Marbled White is one of the most beautiful of British
butterflies. Its
very distinctive chequered black and white pattern is quite different to that of
most other Satyrines, which tend to be patterned in shades of brown and orange.
The pattern is easily remembered by insectivorous birds, and is probably a form
of aposematic ( warning ) coloration, which functions to advertise the toxic
nature of the butterfly.
The sexes can be distinguished by examining the dark peppered bands on the
underside - in the male these are a neutral grey colour, while in the female
they are a warm greyish brown. Neither sex is prone to much in the way of
variation, although entirely black or entirely white forms are known, but these
and intermediate forms are exceptionally rare.
This species
is distributed across much of Europe, but is absent from Portugal, most of
Spain, most of the Mediterranean islands, and Scandinavia. Beyond Europe it
occurs in northern Africa, Turkey,
Georgia, Armenia and Azerbaijan.
There are 6 other very similar Melanargia
species that occur in Europe with which the butterfly can easily be confused. In
the French Pyrenees the butterfly is known to regularly hybridise with the
Iberian Marbled White Melanargia
lachesis, producing
infertile offspring.
Habitats
In Britain this species is confined mainly to southern and south-western
counties of England. A few scattered colonies still exist in Yorkshire, south Wales
and the Midlands, but the butterfly's range has contracted considerably, due
mainly to loss of habitat.
It breeds primarily on
well drained chalk grasslands, typically occurring in huge colonies numbering
hundreds or even thousands of individuals. The highest numbers occur on un-grazed or
very lightly grazed sites where the grasses grow waist high. Such habitats
include cliff-tops, undercliffs, steep south-facing
slopes, abandoned quarries, and ancient Iron Age hill forts. Smaller colonies
numbering a few dozen adults exist in certain woodlands
where they breed along unmown grassy avenues or in large clearings or permanent glades.
Although populations are normally very localised, the butterfly has excellent
powers of dispersal, and is able to colonise motorway embankments, railway
cuttings and similar such wild grassy sites in southern England.
I also regularly see singletons
wandering across certain New
Forest heaths.
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Marbled White
Melanargia galathea female, Ballard
Down, Dorset |
Lifecycle
The Marbled White is
single brooded throughout it's range, emerging in late June and throughout July.
By early August only a handful remain on the wing at most sites, although at
cool windswept coastal grasslands it is often possible to find a few fresh
specimens even in mid-August.
Most butterflies attach
their eggs to specific plants, but Marbled White females are unusual because
they drop their eggs randomly
onto the ground as they fly in and out amongst tall grasses.
The
eggs are globular and whitish. They are laid in July and August, and hatch after
about 2 - 3 weeks.
After eating it's
eggshell, and nibbling at fine grasses for a few days, the larva enters
hibernation, spending the winter months hidden at the base of grass clumps. It
awakens in March, and feeds at night, primarily on red fescue Festuca rubra and sheep's fescue Festuca ovina,
and usually rests by day in a head-downwards position low down on grass stems.
When older it hides at the base of
grass clumps, emerging at dusk to feed on coarser grasses such as cocksfoot Dactylis glomerata, tor grass Brachypodium pinnatum,
and timothy Phleum pratense.
The
mature larva is whitish-brown or yellowish-green, marked with a series of thin
dark lines along the back and sides. In both forms the head is brown.
The
pale ochreous or brownish chrysalis is formed on or just below the surface of
the soil. The pupal stage lasts about 3 weeks.
Adult behaviour
Marbled Whites emerge at the very beginning of July, and
remain on the wing until early August. They
fly in a lazy fashion,
advertising their presence as they flutter above and between tall
grasses. Both sexes
nectar for long periods, mainly at knapweeds, thistles, small
scabious and bramble, but
will also visit hawkbit, ox-eye daisy, hemp agrimony,
yarrow, wood spurge, and rosebay willowherb.
The sexes mix freely and there does not appear to be any form of
ritualised courtship or territorial behaviour. It is likely that
females are mated almost immediately after making their maiden
flight. Copulated pairs can be found settled amongst grasses or
low herbage in late morning, and remain paired for at least half
an hour before parting. If disturbed they will fly a short
distance, with the female carrying the male in flight. When
settled the female tends to partially or fully open her wings,
while her partner keep his wings firmly closed.
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Melanargia galathea
with parasitic red mites
Trombidium breei
attached to the thorax.
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It is common to find Marbled
Whites that have one or more bright red parasitic mites clinging
to the thorax, head or abdomen. Studies have shown that these
mites
Trombidium breei
are harmless to the butterfly, having no
detectable effect on the flight performance, orientation ability
or lifespan. The same species of mite parasitises several other
grassland butterflies including Meadow Brown, Gatekeeper, Common
Blue, Chalkhill Blue, Adonis Blue and Small Skipper.
Marbled Whites usually feed and rest with wings closed, but
on hazy afternoons, or overcast days they can be seen basking with wings open,
settled on low herbage or amongst tall grasses. As dusk
approaches, they move to sheltered areas and settle on grass-heads
or knapweed flowers, where they roost
in a head-downwards posture, often with several ( usually of the
same sex ) sharing the same grass-head.
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