Butterflies of Britain
Family - NYMPHALIDAE
Tribe - NYMPHALINI
Large Tortoiseshell is widely distributed in Europe, and common in
the Mediterranean region where it breeds in open woodland areas. It
also occurs in Morocco, Algeria and Tunisia; and across temperate
Asia from Turkey to Kazakhstan and the foothills of the Himalayas.
It can confused with the similar Yellow-legged
Tortoiseshell Nymphalis xanthomelas
which has much brighter and redder colouring, and enlarged blue
lunules on the hindwings. The latter species is only found in
eastern Europe and temperate Asia, where it breeds in wooded river
valleys. Old records of it's occurrence in Britain are dubious.
A century ago the Large
Tortoiseshell was a common butterfly in southern and eastern
Britain. It had always been subject to periodic fluctuations in
abundance, but declined very suddenly in the early part of the 20th
century, and apart from a short period of abundance in the 1940's
By the 1970's it had become a great rarity.
The butterfly's decline was
originally attributed to increased parasitism but I believe this is
unlikely. Parasitoid / host abundance is normally cyclic, and linked
to the differing climatic requirements of host and parasitoid. After
a period of parasitoid-induced scarcity, butterflies generally
recover and return to abundance until climatic conditions again
favour the parasitoid.
Whatever the cause of the decline, it was certainly
exacerbated by the arrival in Britain in 1976 of a particularly
virulent strain of Dutch elm disease, which rapidly proceeded to
almost eradicate the main larval foodplants wych elm
and English elm
The disease arrived in
Britain on logs imported from North America, and quickly spread
across the country, transported by Scolytus
elm bark beetles. These live
under the bark, and propagate an ascomycete microfungus
Ophiostoma novo-ulmi which is
responsible for the disease.
1990 the Large Tortoiseshell was considered to be either extinct or
on the verge of extinction in the UK. It has been suggested by some
that it still maintains its presence as a breeding resident in
southern England, but that populations have become reduced to the
point where the butterfly is now unobservable. It seems very
unlikely though, as the very conspicuous larval nests would surely
still be found occasionally. None have been reported in Britain for
Since 1998,sporadic sightings of adults have been reliably reported
from sites along the south coast of Hampshire and Dorset. Most of
these records have referred to very worn post-hibernation insects
seen in early spring. It is unknown whether these represent the
progeny of migrants or of captive bred stock. In June / July 2007
fresh specimens were seen at several locations on the Isle of Wight
and scattered along several miles of the Hampshire coastline.
Records of overwintered specimens from other coastal sites every
spring from 2007 to 2012 appears to indicate that the butterfly is
now breeding regularly in low numbers on the Isle of Wight and
possibly elsewhere long the south coast although no larvae have been
recorded. It is however possible that one or more amateur breeders
may be releasing captive-bred European livestock of this butterfly
in an attempt to re-establish the species in Britain.
In Europe the Large Tortoiseshell is usually
encountered as singletons. It is encountered widely but never in
numbers. It is a highly mobile species and breeds in forests and
along hedgerows where elms Ulmus glabra
& U. procera, sallow
Salix caprea, poplars
Populus alba & P.
wild cherry Prunus avium,
aspen Populus tremula grow.
adults emerge in late June or early July, but are only active for
about a fortnight, as they enter hibernation very early - typically
in late July, and are not seen again until the following spring.
The eggs are laid in April, and hatch after about
3 weeks. They are laid in large batches in a neatly arranged ring
around twigs, about 2-4 metres up, on the sunny side of various
trees, but particularly on wych elm Ulmus
larvae are black, covered with sharp orange spikes and peppered with
tiny white dots, giving them a greyish appearance. They live
communally in conspicuous silk webs spun on the twigs of the
foodplants. If they are disturbed by a bird the whole group jerks in
unison. As they grow older they split into smaller groups, and
become solitary just prior to pupation.
fully grown in early June, the larvae descend from the treetops, and
wander a short distance to pupate. The pupa is brown, marked with
gold spots, slightly spiky in appearance, and resembles a withered
dead leaf. It is formed hanging by the cremaster from twigs or
branches on the lower part of various bushes and trees. In Turkey I
have found them commonly suspended from the walls and eaves of
buildings. In my experience at least 60 percent of pupae are found
to be parasitised.
Males are seen as
solitary individuals, usually either in flight, or when basking on
bare ground in lightly wooded habitats. In Britain they have been
reported nectaring at sallow catkins in spring, and bramble blossom
and various herbaceous garden plants in summer.
habitually bask on tree trunks, often in a head-downwards posture. The
males patrol along wood edges until they locate a female, and then
settle beside it. The female then flies off, with the male in hot
pursuit, until after an hour or more the pair settle on a tree trunk
and copulate. They remain paired all afternoon, and possibly
In Europe they
are sometimes seen flying around the tops of sallows, elms and
poplars, but are normally encountered in flight, when dispersing in
search of breeding sites.
In western France I've
observed them flying in inhospitable terrain including motorway car
parks, petrol stations and town centres, indicating that the species
is highly mobile and probably migratory in behaviour.
Dijon in central France I once found 3 Large Tortoiseshells clustering
together in the company of several bees and a dozen Woodland
Graylings, all feeding at a sap run on a hedgerow hawthorn. While
feeding the Large Tortoiseshells nervously fanned their wings, but
made no attempt to fly away even when I approached very closely.
However on other occasions when I've encountered this species, they
have been extremely wary.
Turkey I have found recently emerged butterflies hanging from twigs
along dry river beds. They remained aestivating on the twigs for
several days in late May.