Butterflies of
Britain & Europe
Gatekeeper
Pyronia tithonus
LINNAEUS, 1771
Family - NYMPHALIDAE
subfamily -
SATYRINAE
Tribe - SATYRINI
subtribe - MANIOLINA
introduction
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habitats |
lifecycle |
adult behaviour
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Gatekeeper
Pyronia tithonus, male,
Stansted Forest, West Sussex, England |
Introduction
The Gatekeeper is also
known by the name Hedge Brown, and at various stages in history has been called
"Small Meadow Brown", "Hedge Eye" and "Large Heath" - the latter name now being
applied to a different species Coenonympha tullia.
For more information see
British
vernacular names.
This
is a very common and widespread butterfly which is
distributed throughout much of Europe, but absent from northern Britain,
Scandinavia, and south Italy. It is found in the Pyrenees, but absent from the
Alps, and from most of the Mediterranean islands. Beyond Europe it occurs in the Rif mountains of Morocco, and in western Turkey.
Male Gatekeepers, in common with several other Satyrines ( "browns" ) have a prominent band of
dark androconial ( pheromone producing ) scales running diagonally across the forewings, and are noticeably smaller than
the females. Neither sex are prone to much variation in colour or patterning,
although there can sometimes be a small third ocellus below the usual pair on
the forewing.
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Gatekeeper
Pyronia tithonus, male ab
multiocellata ( note additional spots on
forewings ) |
The
Gatekeeper cannot be mistaken for any other British species, but both sexes are
similar on the upperside to the Southern Gatekeeper P. cecilia,
which occurs in Spain, Portugal, southern France, Italy and north Africa. The
underside hindwings of the latter species are quite different, being dark brown,
heavily mottled and striated with white.
Habitats
In southern Britain the
Gatekeeper can be found almost anywhere where grasses grow in association with
bushes. It can be exceedingly common on scrubby grassland, in
woodland clearings and glades, scrubby heathland, sand dunes, old quarries, and
along railways cuttings, hedgerows and country lanes, always favouring sheltered sunny situations.
In northern Britain however the butterfly is very rare. This pronounced
north-south divide is probably controlled by the need for larvae to develop
quickly during the spring and early summer when night temperatures in southern
Britain are higher than in the north. It is also likely that parasite / host
synchrony is climatically influenced, and this may affect the ability of the
species to survive in northern areas.
The butterfly has become
scarcer in areas where verge mowing, hedge removal and the misguided and
obsessive "tidying up" of the countryside has occurred. Nevertheless
it is capable of
recovering and recolonising habitats such as overgrown gardens, railway cuttings,
quarries, and regenerating woodland clearings. At Broadmarsh in Hampshire for
example it
took about 5 years to colonise and become exceedingly common at a newly created coastal landfill site,
having dispersed from a nearby large colony at Farlington Marshes.
Lifecycle
The adults emerge in late
June and July, and lay their eggs singly on grasses growing in sheltered and sunny positions
at the base of hawthorn, bramble and blackthorn bushes where grasses
grow quite tall,
and
ungrazed by rabbits, sheep or deer.
The eggs are spherical
with about 16 vertical ridges, and are pale yellow when first laid, but within a
couple of days develop irregular brown
blotches. They hatch after about 14 days.
The
caterpillars feed nocturnally on the blades of various grasses including red fescue Festuca rubra,
meadow grass Poa pratensis,
couch Agropyron repens,
and bristle bent Agrostis setacea, always eating
only the finest leaf blades. In daytime they hide at the base of grass tussocks,
in a head-downwards posture. They enter hibernation in September when quite small, and
re-awaken in March or April, feeding slowly and achieving full growth by late May or
early June. The mature larva is dull greyish olive or sometimes a dirty buff
colour, with a dark line along the back and thinner dark lines along the sides.
The
chrysalis is a pale straw colour, marked on the wing cases and thorax with
blackish streaks. It hangs by the cremaster, with the shrivelled larval skin
still attached, from twigs or dry grass stems at the base of bushes. The pupal
stage lasts about 2 weeks.
Adult behaviour
In overcast conditions, or in hazy sunshine, Gatekeepers bask on
the foliage of bracken, bramble and other low vegetation.
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Gatekeeper
Pyronia tithonus, female,
Stockbridge Down, Hampshire, England |
During
sunny weather Gatekeepers flit from flower to flower, nectaring for a few
seconds at a time at privet, bramble blossom, dogwood, ragwort,
fleabane, hemp agrimony, marjoram and various other plants.
Copulation takes
place without any observed courtship ritual, and lasts for about
an hour, during which the butterflies remain stationary with their
wings closed.
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Gatekeeper
Pyronia tithonus, copulated pair,
Ballard Down, Dorset, Hampshire, England |
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