Butterflies of Britain
Family - LYCAENIDAE
subfamily - THECLINAE
Tribe - EUMAEINI
Quercusia quercus female, Rowland Wood,
© Nigel Kemp
The Purple Hairstreak is
a very widespread species occurring throughout Europe with the
exception of northern Scotland, northern Sweden and Norway. It's
range extends across the Middle East and temperate Asia as far as
the Ural mountains and Kazakhstan. It also occurs in Morocco and
The only other European butterfly which could be
confused with quercus is the Spanish
Hairstreak Laeosopis roboris, which is
found only in Spain, Portugal and southern France. It is similar on
the upperside, but the underside lacks the white hairstreak line,
and has a prominent band of orange, white and black submarginal
Quercusia quercus, Fermyn Wood,
In Europe and
north Africa the Purple Hairstreak breeds almost anywhere that oaks
grow, even in hot arid scrubland bordering the Mediterranean.
In Britain it
is found primarily in southern and central England, and throughout
Wales. It also occurs in widely scattered colonies in northern
England, in the Scottish Highlands, and in Ireland.
Heavily wooded areas
often have enormous populations of this butterfly. I have
also found a
few colonies on isolated stands of oak on heathland in the New
Forest, and in suburban parks, although these are likely to be
Purple Hairstreaks are single brooded throughout their range, but
have a protracted emergence beginning in late June, and lasting well
eggs are laid singly on the terminal buds and twigs of oaks.
Sometimes 3 or more eggs can be found together on a single bud, but
these are usually the result of repeat visits by a single female,
rather than having all been laid at the same time. The butterflies
oviposit at all heights on the trees, but young bushy growth on the
crown or the south side of the trees is heavily favoured. In a study
carried out in 1987, I
examined several hundred wind-felled oaks in Hampshire and West
Sussex. I found that eggs were present on about 95 percent of the
English oaks Quercus robur examined,
but less than 5 percent of the sessile oaks Q.
petraea held eggs, and none at all were
found on red oak Q. rubra, turkey oak
Q. cerris, or holm oak
Q. ilex, although this latter species
is certainly used in southern Europe.
mainly laid on trees along woodland edges, or bordering forest
tracks. Mature oak standards in hazel or sweet chestnut coppice were
also frequently used. Hedgerow oaks are less commonly used.
greyish eggs over-winter, and hatch in late March and early April
when the buds begin to open. Immediately after hatching the young
larvae burrow into the leaf buds to feed, but when older they feed
on the leaves. Each larva spins a thin web of silk around a clump of
leaves, resting within it by day, and emerging at night to feed.
When fully grown the larva is plump, and has a pair of raised humps
on each segment. It rests at the base of leaf clumps, and frequently
has ants in attendance.
Ants, particularly Lasius
niger, also attend the pupa, which is formed on the ground.
The ants cover the chrysalis to hide it, or transport it into their
nests at the base of oak trees. Inside the ant nest the pupa is
protected from predators.
adult butterflies emerge in the early morning, and can sometimes
then be seen basking on the ground or on foliage beneath oaks.
Quercusia quercus, Fermyn Wood,
In southern England
the Purple Hairstreak is a very common butterfly but its
semi-crepuscular nature and its habit of spending most of its
time high in tree tops can create the illusion that it is
scarcer. The true abundance of the butterfly can be illustrated
as follows :
7.00-7.30pm on 2nd July 2008, during a walk around Whiteley
Pastures in Hampshire I counted 173 Purple Hairstreaks in flight
around the tops of oak trees. The mature broad-crowned oaks
produced the highest counts, with between 8 - 12 seen in flight
above each tree, while the smaller and more spindly trees
typically hosted at least 3 or 4 specimens. These figures only
represent butterflies seen in flight, and it can be safely
assumed that for each specimen in flight there must have been at
least another 3 or 4 at rest which escaped detection. During the
limited time available I was only able to look at about 0·5% of
the oaks in the wood ( i.e. those along a half-mile stretch of
one particular track ). If my logic is correct this means the
total population of Purple Hairstreaks at Whiteley Pastures on
that particular day was possibly in excess of 103,800
butterflies ( multiply 173 x 3 to get an estimate of butterflies
along the section of track that I visited, and multiply that
figure by 200 to include the total number of mature oaks in the
The butterflies are
sedentary in nature, and normally only seen when small groups of them
flutter around the tops of oaks in the late afternoon, presumably
indulging in mate location and courtship. When seen in flight the
butterflies appear silvery, like spinning coins.
During the rest of the
day they tend to sit motionless, perched on foliage in the canopy,
feeding on the sugary secretions of the
aphid Phylloxera quercus, which coat the
upper surface of the oak leaves. This secretion "honey dew" is
undoubtedly the major source of sustenance for adults.
occasionally found adults nectaring at hogweed or bramble flowers, or
imbibing mineral-rich moisture from mud or gravel tracks. I've also
found them many times at rest on bracken beneath oaks, presumably
having emerged from the ground, and crawled up the bracken stems to
hang and dry their wings.
blustery days Purple Hairstreaks occasionally get blown down from the
trees, and can then be found amongst grasses and low growing plants.
Particular trees within a wood tend to attract aggregations of adults,
which can be seen flying across forest tracks from other oaks. These
assemblies are probably related to courtship behaviour, as in the case
of Purple Emperors and various other species.
Quercusia quercus, female resting on oak leaf, Havant Thicket,