Butterflies of
Europe
Blue-spot Hairstreak
Satyrium spini
DENIS & SCHIFFERMULLER, 1775
Family - LYCAENIDAE
subfamily -
THECLINAE
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Blue-spot Hairstreak
Satyrium spini, Velebit Mts, Croatia
© Peter Bruce-Jones |
Introduction
There are 64 described species in the genus
Satyrium, which has at various times been known by the
invalid synonyms Neolycaena,
Nordmannia,
Pseudothecla and Strymonidia.
The genus occurs across the temperate, sub-arctic and subtropical
regions of the northern hemisphere.
There are 7 species in Europe -
acaciae, ilicis,
esculi, spini,
w-album, pruni
and ledereri; of which only
w-album and
pruni occur in Britain.
Satyrium spini
is found in Portugal, Spain, France, Italy, Switzerland, Austria,
Germany, Poland, Hungary, Croatia, Greece, Turkey, and east to
Iraq and Iran.
Habitats
This species is found mainly in hot, dry, scrubby habitats
including woodland clearings, grassland, lightly wooded
mountainsides and bushy meadows; typically at altitudes between
sea level and about 1500m, although colonies occur as high as
2000m in Greece.
Lifecycle
The Blue-spot
Hairstreak is single-brooded, flying from late May to early August
depending on locality and altitude.
The eggs are
usually laid in groups of between 3-5 on woody twigs
of the foodplants, usually close to a fork. They are a dirty
whitish colour with a prominent micropyle, and are covered in a
fine network polygonal depressions. The caterpillars are fully
formed within the eggs shortly after they are laid in the summer,
but do not hatch until the following March.
The caterpillar is woodlouse-shaped but with well defined
segments. It is green, slightly hairy, and marked along the back
with a pair of broken cream stripes. There are a series of
forward-slanting suffused creamy diagonal bars along the sides,
and a solid cream line below the spiracles. If feeds on
Rhamnus ( buckthorn ), usually
resting on the underside of the stems or leaves. In common with
most other Lycaenidae species the larvae are tended by ants which "milk"
them to obtain sugary substances secreted from their dorsal gland.
The chrysalis is
attached by a fine silken girdle to the underside, or occasionally
to the upperside, of a living leaf of the foodplant. It is pale
brown, heavily speckled. It is plump in form, rounded at the head
and tail, and covered in short bristly hairs.
Adult behaviour
The adults can easily be overlooked due to their reclusive and
sedentary nature, and are normally only seen in two's or three's,
although occasionally colonies of 100 or more can be found.
Both sexes nectar
at
the flowers of a wide variety of herbaceous plants including wood
spurge, yarrow, lavender, stonecrop and thyme. They also visit the
flowers of bramble bushes.
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