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Butterflies of
Britain & Europe
Heath Fritillary
Mellicta athalia
ROTTEMBURG, 1775
Family - NYMPHALIDAE
subfamily -
NYMPHALINAE
Tribe - MELITAEINI
subtribe -
EUPHYDRYINA
introduction
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habitats |
lifecycle |
adult behaviour
Text and photographs protected by Copyright © Adrian
Hoskins 2007-2008, and must not be reproduced or published in part
or in whole elsewhere in any form without written permission from
Adrian Hoskins. Breach of copyright will be pursued by litigation.
Website designed, produced and owned by
Adrian Hoskins
Heath Fritillary
Mellicta athalia, male on sweet
chestnut, Kent, England
Introduction
The
Heath Fritillary is a common and widespread species found throughout continental
Europe including northern Scandinavia, but is absent from the southern Iberian peninsula and the
Mediterranean islands. It's range also extends eastward across temperate Asia to
Japan. In Britain it is a scarce and localised species confined to a few of the
southern counties.
It
cannot be confused with any other British species, except perhaps the Glanville
Fritillary, which only occurs on the Isle of Wight and the Hampshire coast -
areas from which the Heath Fritillary is absent.
Heath
Fritillary
Mellicta athalia, male, Essex,
England
In
Europe and temperate Asia there are a large number of other species with which
the Heath Fritillary can be confused. These include at least 6 other members of
the genus Mellicta,
and several members of the allied
Melitaea.
The differences between some of the species are so minor that it takes a very
experienced eye to tell them apart, and the use of a well illustrated field
guide is essential.
Heath
Fritillary
Mellicta athalia, female, Kent,
England
Habitats
In Europe the butterfly
can be found in a wide range of habitats including woodland, hay meadows,
sub-alpine pastures, scrubby grassland and roadside verges.
In Britain it is at the
edge of it's range, and is restricted to a very limited range of habitats. It
was formerly widespread in southern counties of England, and was once abundant
in Killarney, Ireland, but loss of habitat, and possibly other factors including
climate and parasitism, led to it's decline. Now, in the first decade of the
21st century, it is restricted to just a handful of sites in Kent, Devon and
Cornwall, and to a few sites in Essex where it was re-introduced as part of a
conservation program.
In
Kent and Essex the butterflies are confined to a complex of small to medium
sized woodlands which are managed as sweet chestnut coppice, with a fairly open
canopy of oaks. Here the butterflies breed in small temporary clearings, where
the parasitic herb cow wheat, which is the foodplant of the caterpillars, grows
profusely.
An
unpublished survey of north Kent in June / July 2007 by Hoskins and Meredith
found that the species is present in almost all of the woodlands north and west
of Canterbury. A total of 13 separate colonies were located, each comprising
between 10 - 60 adults per day during peak flight season.
The
sites on Exmoor in Devon are entirely different in nature - sheltered hillsides
and lightly wooded valley bottoms where the foodplant grows amidst bracken or
heather.
Heath
Fritillary
Mellicta athalia, female at rest on grass stem,
Essex, England
Heath
Fritillary
Mellicta athalia, male basking on bracken, Kent, England
Lifecycle
The Heath Fritillary is single
brooded in Britain and northern Europe, but double brooded in
Spain, Portugal, southern France and Italy.
In Britain the adults emerge in late May /
early June ( Devon ), or in mid-late June ( Kent and Essex ).
The females
lay their eggs in large untidy batches on the underside of
bramble, foxglove or other large leaves low on the ground.
Sometimes they lay under dead fallen leaves of
sweet chestnut, in the vicinity of the larval foodplants, but
rarely on the foodplants themselves.
The eggs, which are yellow at first, but later
turn greyish, hatch after about 10 days.
The young caterpillars spin thin
silk webs over the leaves of the foodplants, and bask on these
in groups of about a dozen or so. They enter hibernation in
September when still small, spending the winter clustered
together on dead leaves on the ground. In March they awaken, and
resume feeding on the leaves of cow wheat
Melampyrum pratense, sometimes
supplemented by germander speedwell
Veronica chamaedrys
or foxglove
Digitalis purpurea.
In Cornwall the foodplant is usually plantain
Plantago lanceolata.
The
older larvae, which live solitarily, are quite distinctive, with
black bodies and rows of short white and yellow spikes along the
back and sides. They become full grown in early May, when they
feed and bask openly on the upper surface of leaves of the
foodplants.
The chrysalis, which is formed
amongst dead leaves and twigs on the ground, is white, decorated
with numerous small black and yellow spots. The pupal stage is
short, usually only about 8 - 12 days.
Heath Fritillary
Mellicta athalia, copulating pair,
Essex, England
Adult behaviour
Adults are usually found flying in groups of between 10 - 100, in isolated pockets within their habitats. Sometimes when breeding sites are well managed and climatic conditions are suitable, much larger populations can arise, comprising of several hundred individuals.
Males patrol lazily about the habitats searching for freshly emerged females. Copulation takes place in late morning. I have found mated pairs on several occasions, often sitting in exposed positions on bramble flowers or on the terminal leaves of low growing plants. The pheromones emanated by the females appear to be quite powerful, often attracting several additional males, which gather around the copulated pair, trying to force themselves on the female.
Heath Fritillaries Mellicta athalia, Essex, England
Heath Fritillary Mellicta athalia, male at roost on red clover, Kent, England
The butterflies will nectar at various flowers including bugle, heather, lesser stitchwort, and buttercups, but show a strong preference for hawkbit and bramble blossom. Females often feed avidly for several minutes at a time, but males tend to flit more frequently from flower to flower. On several occasions I have found adults in the grip of crab spiders Misumena vatia, which lie in ambush on the bramble flowers.
Even in warm sunny conditions the butterflies are decidedly lethargic, and rarely attempt to fly more than 2 or 3 metres at a time. They spend long periods resting with wings closed on the foliage of sweet chestnut, bramble or oak saplings. In hazy or lightly overcast conditions both sexes will bask on low foliage. It is very common to find 2 or 3 Heath Fritillaries basking side by side on bramble or sweet chestnut leaves.
Heath Fritillary Mellicta athalia, males basking on bramble leaves, Essex, England
Heath Fritillary Mellicta athalia, male at roost on soft rush, Kent, England
Small groups of adults can be found at dusk on dry days, roosting on sedges, rushes, or on the terminal foliage of low-growing herbs. I have also found them roosting on grass-heads, red clover, bracken fronds, or amongst the foliage of coppiced sweet chestnut.
Heath Fritillary Mellicta athalia, at roost on jointed rush, Kent, England
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