Butterflies of Britain
Family - LYCAENIDAE
subfamily - THECLINAE
Tribe - EUMAEINI
Callophrys rubi, male, Magdalen Hill
Down, Hampshire ©
The genus name of this delightful little butterfly -
Callophrys - is Greek for "beautiful
eyebrows" and the species name rubi
refers to Rubus ( bramble ), one of the
The Green Hairstreak never displays it's brown upperside except when
in flight. The green colour of the underside (
like the blues and coppers of other Lycaenids ) is produced
by light refracting and reflecting from a
microscopic lattice within translucent
wing scales. The iridescent colouring varies in
hue according to the directional qualities of the light
and the angle of view. The butterfly can thus appear to be
metallic apple-green, turquoise or emerald, when viewed from various
Some individuals known as form caecus
have plain undersides, but on others the wings are marked with a row
of white dots, often edged with reddish - these are called form
The sexes are almost identical, but the male has a small patch of
scent scales in the discal cell of the upperside forewing.
This is also visible in certain lighting conditions in the form of a
little raised pad in the cell on the underside.
Callophrys rubi, male, Magdalen Hill
Down, Hampshire ©
Callophrys rubi, female, Cerne Abbas,
The butterfly is widely distributed in Europe,
all the way from the Mediterranean islands to the far north of
Norway and Sweden. It also occurs in Morocco and Algeria, and in
most of temperate Asia. There are many closely related species
elsewhere in the world, including the unfortunately named Sad Green
Hairstreak Cyanophrys miserabilis of
North America, and several neotropical species.
In southern France, Spain, Portugal, Morocco and
Algeria it can be confused with Chapman's Green Hairstreak
Callophrys avis, which occurs in dry
scrubby areas and feeds as a larva on Arbutus.
They can be separated by examination of the eye borders, which in
rubi are white, but in
avis are reddish. The white dotted line
on the underside is placed centrally in avis,
but in the post-discal area in rubi.
occurs throughout most of the British Isles, but is quite localised,
although the range of habitats and larval foodplants used is very
It is commonest on dry heathland, and on scrubby south-facing
hillsides or warm sheltered valley bottoms, particularly favouring
habitats with hedgerows of hawthorn, blackthorn,
elder or gorse.
Most colonies are small comprising no more than about 10-20 adults
at peak season. Many are even smaller, particularly at
marginal habitats - e.g. along
railway cuttings, in woodland clearings or
At a few moorland sites in Cornwall and Cumbria however much larger
populations exist, numbering dozens or even hundreds of adults.
South facing chalk
grassland slopes like this are ideal Green Hairstreak habitats ©
The butterflies emerge in early April in forward seasons, but may be
delayed until mid May in cool wet springs. They normally remain on
the wing until early June.
widely over their habitat, laying their eggs singly on the
leaves or flower buds of the various
foodplants, including bird's foot trefoil
Lotus corniculatus, common rockrose
Helianthemum chamaecistus, dogwood
Cornus sanguinea, buckthorn
Rhamnus catharticus, gorse
Ulex europaeus, and broom
Cytisus scoparius. On moorlands and
heaths the main foodplant is bilberry
Vaccinium myrtillus, and in woodlands bramble
Rubus fruticosus is commonly used.
At Levin Down in Sussex, I watched a particular female ovipositing
over a half hour period on a hot sunny morning in May
2006. She flew back and forth over a 20x50 metre strip of
hillside, carefully selecting each egg-laying
site, always choosing to lay on leaves of rockrose, despite the
presence of bird's
foot trefoil and other known foodplants.
At Magdalen Hill Down, I watched another female behave in a similar
manner, depositing her pale green eggs meticulously onto the upper
surface of rock rose leaves, inserting them into the crevice formed
where the base of the leaves emerges from the stems.
At both sites the eggs were laid on plants
growing on ant-hills. This is probably
because ant-hills tend to be warmer than surrounding areas, but
could also be influenced by an
association between the larva and ants - many Lycaenid larvae are
"milked" by ants, which drink a sweet
secretion produced from a "honey gland"
on the back of the larva.
Callophrys rubi, male, Purbeck hills,
Like other Lycaenid larvae, that of the Green Hairstreak is plump,
like a woodlouse. It is green, and marked with rows of yellow dots
on the back and sides. The larva feeds on the flower buds, flowers
or tender young leaves of common rockrose, gorse, bilberry, bird's
foot trefoil, dogwood, broom and various vetches.
At some sites the larvae feed on buckthorn berries, in which they
make a hole through which they extract the contents.
The larva leaves the foodplant to pupate just under the surface of
the ground, often where there are stones or fallen leaves.
The pupa has the
ability to produce a squeaking noise - this was once thought to be a
defence mechanism against ants and beetles, but research on other
Lycaenids that also share this behaviour suggest that the pupa is
actually "singing" to attract the attention of ants, which carry it
into their nests below the ground. The pupa secretes a sugary
coating which the ants drink, and in exchange the pupa gains
protection from other insects that would not dare enter the ants
period is from
April until early June at the warmest sites; or from early May until
late June at cooler or northern sites.
Callophrys rubi, Magdalen Hill Down,
and females behave quite differently. Males establish territories,
typically perching on gorse flowers, or on the foliage of hawthorn,
various other bushes,
often at the bottom of hills.
On sunny mornings they use these perches as vantage points from which
up to intercept
small insects, including bees, flies, and various butterfly species,
as well as other Green Hairstreaks.
perching they regulate their body temperature by tilting their wings -
in cooler conditions they are angled to present the maximum wing area
to the sun but in hot conditions they are angled edge
on to minimise heat absorption. This lateral-basking
has the additional advantage that the wings cast no give-away shadows,
helping the already superbly camouflaged butterfly to
even more perfectly against its background and avoid being detected by
several males will have overlapping territories, so male-male
encounters are frequent.
they engage in a
zipping about in tight circles,
each trying to outwit and outmanoeuvre the other with constant changes
of direction. Each male changes his territory several times throughout
the day in response to the changing position of the sun which causes
each perch to become shaded at some stage. Thus the butterflies
frequently find themselves intruding into each other's territories and
often both males believe they have "ownership" of a particular spot.
At such times their battles can be protracted and intense. The pair
will commonly spiral rapidly to a height of about 4 metres, then break
away. Invariably however they soon meet again and continue the battle
which may last for several minutes. During this time they may chase
each other up to 4 or 5 metres horizontally from the point where the
conflict began. Eventually the weaker male gives up and leaves the
vicinity, and the victor returns to his original perch.
have not observed courtship,
it is likely that the sexes copulate without any pre-nuptial
ritual. On several occasions I've
found copulated pairs settled on low herbage, but they are difficult
due to the very effective cryptic colouration.
Females spend most of their time fluttering
the ground in search of egg-laying
sites, and are seen far less often than the males.
sexes nectar at a wide range of spring flowers including bird's
horseshoe vetch, common vetch,
holly, wayfaring tree, bluebells,
I have observed Green Hairstreaks flying around elms and field
at the bottom of chalk hills
and settling for long periods on
foliage on the higher branches
of small oaks,
but have not been able to determine whether both sexes indulge in
rubi, Cissbury Ring, Sussex ©