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Butterflies of
Britain & Europe
Speckled Wood
Pararge aegeria tircis
BUTLER, 1867
Family - NYMPHALIDAE
subfamily -
SATYRINAE
Tribe - SATYRINI
introduction
|
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
Speckled Wood
Pararge aegeria, male,
Powerstock, Dorset, England
Introduction
This common woodland
butterfly was originally known in Britain as the Enfield Eye or Wood Argus. The
name Speckled Wood first appeared in 1766, in Moses Harris's famous book The
Aurelian.
The butterfly is widely
distributed in Europe, but absent from sub-arctic areas of Norway
and Sweden. Beyond Europe it occurs in the Atlas mountains of north Africa and extends
into Asia as far east as the central Ural mountains.
The
British and northern European subspecies
tircis
is marked with pale creamy spots, but in southern Europe the normal form of the
butterfly has the wings patterned with large orange blotches, and can be
mistaken for the Wall Brown
Lasiommata megera.
There are 2 other very similar
Pararge species -
xiphiopides
which is endemic to the Canary Islands, and
xiphia
which is endemic to Madeira ( where
aegeria
also occurs ).
The
Speckled Wood is unique among British butterflies in that it can hibernate as either a
caterpillar or chrysalis. Consequently the spring emergence of adults
tends to be very staggered. At any individual site however the adults tend to emerge in
synchrony, which implies that the hibernation stage is dependent on habitat and
local climate, rather than being random.
The
butterfly usually produces 2 generations a year in Scotland, or 3 generations a
year in southern Britain, where it can be seen at any time between March and mid
November.
Beech
woodland with dappled sunlight - a Speckled Wood habitat in southern
England
Habitats
In Britain the Speckled
Wood is regarded as a common woodland butterfly, which breeds in damp areas
where dappled sunlight filters through the trees. It can commonly be seen
basking on low foliage, or on forest paths in deciduous woodland, but is quite
tolerant of shade and can also be found in conifer plantations, where it breeds
along grassy rides.
In recent years it has
increasingly expanded into more open habitats, and can regularly be seen in
gardens, along hedgerows, and even in bushy areas of open grassland.
Lifecycle
There are either 2 or 3
broods per year in Britain, depending upon location. Normally the first adults
appear in late March. The emergence is very protracted however, extending well
into June, and overlapping with the second brood, which flies between late June
and September. The third brood ( if and when it occurs ) usually begins in
August, but late emerging insects may still be flying as late as mid November.
Individual adults have a lifespan of between about 7-20 days.
The spherical egg is
straw coloured, and finely ribbed. It is laid singly on the underside of grass
blades, always where the grasses are growing in dappled light, usually at the base
of bushes. It hatches after about a week.
Unlike most other Satyrine larvae, which are generally nocturnal, the
caterpillar of the Speckled Wood feeds by daylight. It is pale green, marked
with thin longitudinal yellow and whitish stripes, and is perfectly camouflaged
at rest on grass blades. It feeds on soft grasses, principally cocksfoot
Dactylis glomerata,
couch
Agropyron repens,
wood millet
Milium effusum,
Yorkshire-fog
Holcus lanatus,
creeping soft grass
Holcus mollis,
and wood meadow grass
Poa nemoralis.
The
chrysalis is formed hanging by the cremaster from woody stems, and is variable
in colour, some being pale green, while others can be quite dark, particularly
those of the over-wintering brood.
Speckled Wood
Pararge aegeria, male, Purbeck
Hills, Dorset, England
Adult behaviour
The Speckled Wood flies in shadier habitats than most other British butterflies, and is commonly active on dull overcast days when other species refuse to fly.
Speckled Wood
Pararge aegeria, female, Crab
Wood, Hampshire, England
On sunny mornings males take up residence in areas of woodland where dappled sunlight filters through the trees. Each male selects a "perch" in the form of a sunlit leaf, from which it can survey passing females. During the course of the morning, the changing position of the sun causes the various perching places to be periodically shaded, at which time each male has to move to establish a new perch. Inevitably this results in a high number of male-male encounters.
When males meet, they engage in a sortie, spiralling upwards to the tree tops, after which a "winner" emerges to return to his chosen perch. Experiments have shown that the winning male is usually the one which first established the perch. The intruding male is ousted, and has to establish a new perch elsewhere in the vicinity. In experiments when 2 males have been introduced simultaneously into an area, and both believe they have ownership of a perch, the ensuing sortie can last for many minutes.
Males leave their perches to intercept Speckled Woods of either sex, but generally ignore other butterfly species. When a female is intercepted, the pair settle on foliage, and the female spreads her wings. The male then approaches from below, gently walking onto the hindwings of the female. Butterflies have olfactory ( pheromone-detecting ) sensors on their feet, so this ritualised behaviour may enable the male to "taste" whether or not the female is a virgin.
Copulation takes place in the late morning and lasts for about an hour.
The adult butterflies feed mainly on honey dew ( aphid secretions ) on the upper surface of leaves, typically in ash or oak trees. I have also observed them nectaring at pear blossom, buckthorn, hawthorn and the flowers of the wayfaring tree. The commonest nectar source however is probably wood spurge.
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