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Butterflies of
Britain & Europe
Orange tip
Anthocharis
cardamines
LINNAEUS, 1758
Family - PIERIDAE
subfamily - PIERINAE
tribe -
ANTHOCHARIDINI
introduction
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habitats |
lifecycle |
adult behaviour
Orange tip Anthocharis cardamines,
male, Dunsfold, Surrey, England
Introduction
The Orange
tip, like the primrose and the cuckoo, is a true herald of spring.
It is one of the very few species that are on the increase in
Britain, having spread northwards in recent decades, whilst still
remaining widespread and abundant in the south.
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The orange tips to the male's forewings are believed to be aposematic, acting as
a warning to birds that the butterflies contain toxins
( mustard oils ) derived
from the larval foodplants, garlic mustard and cuckoo flower . Females lack the
orange - they lead much more sedentary and inconspicuous lives so
possibly have less need to "advertise" their toxicity.
It's unlikely that the orange of the male serves any purpose in
mate recognition - in this species it is the male that searches for
the female. The female therefore has no need to visually locate the male.
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There is virtually no variation in the colouring or patterning of
Orange tips, but there is a great deal of variation in size. The
smaller butterflies may result from larvae that have fed on cuckoo
flower - these plants
often
have barely enough foliage to sustain the larvae, and it is
possible that they literally run out of food, and pupate early.
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Orange tip Anthocharis cardamines,
male at violet, Stansted Forest, Sussex |
In Europe
the female Orange tip can easily be confused with the Dappled
Whites
Euchloe ausonia
and E.
simplonia,
although both of these are more heavily marked with green on the
underside hindwings, and have more angular forewings. The only
European species with which the male can be confused is Gruner's Orange tip
Anthocharis gruneri
but that species, which occurs only in south-eastern Europe, is
markedly smaller, and has a more yellowish ground colour.
Elsewhere in the
world there are several other Orange tip species, e.g. Anthocharis sara
from Alaska, A.
cethura
from California, and
A. bieti
from Tibet and Siberia. The last two species have very falcate
apices on the forewings.
Zegris fausti
from Turkestan is also similar in appearance but has a strongly
recurved forewing costa. The 40 African Colotis "Orange tips"
have plain undersides, and are only distantly related.
Anthocharis cardamines is found throughout most of Europe, but is absent
from much of the Iberian peninsula and from
northern Scandinavia. It's range extends eastward across temperate Asia to Amurland and Japan.
Habitats
In southern Britain the Orange tip
can be encountered in almost
any habitat, but is most
commonly seen
in damp sheltered areas where it's larval foodplants grow. These
include riverbanks, ditches, dykes, hedgerows,
damp meadows, fens, railway cuttings, damp woodland glades
and country lanes. The butterflies wander
almost randomly across the countryside, unlike in northern England
and Scotland where they breed in localised colonies, usually close
to river banks.
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When species are near the edge of their natural range they
need to become more specialised in their choice of
breeding sites - open countryside would be too cool for the
Orange tip in northern Britain, but riverbanks provide a
sheltered, warm and humid environment where the butterfly
and its foodplants can flourish. |
In continental Europe the
butterfly is found in a much wider range of habitats including marshland, moors, arid scrub, and on alpine
pastures at altitudes up to 2100m.
Orange tip Anthocharis cardamines,
female at roost on wood spurge
Lifecycle
Orange tips usually begin to emerge in mid April, but can appear
as early as the end of March in an exceptionally warm spring.
Conversely in a cold spring their appearance can be delayed until
late April. The peak flight season for both sexes is mid-May, and
by the end of the month the males have disappeared and just a few
females remain, and may continue flying into very early June. In Europe the flight season is longer, with the
butterflies still on the wing in early July at moderate altitudes
in the Alps.
Weather conditions during the flight season have a great affect on
butterfly abundance the following year. In early seasons
a high percentage of eggs are laid on cuckoo flower
Cardamine pratensis,
but in late seasons the majority are laid on garlic mustard Alliaria petiolata.
Larval survival
is higher on garlic mustard than on cuckoo flower, probably
because the former produces larger and more abundant seed pods.
Hence a late "season" tends to result in higher numbers of adults
being seen the following year.
Anthocharis cardamines - the egg on
the right is freshly laid, that on the left is about 3 days old.
Although cuckoo flower and garlic mustard are the primary
larval foodplants, females occasionally oviposit on charlock, hedge
mustard or watercress; but regardless of the plant chosen, the
eggs are always laid singly, and always in the same position - on
the flower stalks.
Sometimes more than one egg can be found per plant, but this is
unusual, as the butterflies seem able to detect the presence of
eggs that have already been laid.
The eggs are skittle-shaped and greenish-white in colour when
first laid,
but turn to orange after a day or two, and then
finally to grey.
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Orange tip Anthocharis cardamines,
male nectaring at garlic mustard, Stansted Forest, Sussex |
The caterpillars hatch after about 8 days.
When very young they are pale orange, and
feed on the flowers of the foodplants. After the first moult they
become a dull green, and feed on the flower-stalks, and later on
the seedpods and leaves.
When fully grown they are pale bluish
green with a white lateral line, below which the colour changes
to dark green. They habitually rest on
the upper surface of the seedpods, where they are superbly camouflaged.
Nevertheless many are taken by predators - mainly spiders and
birds. The larvae are also parasitised by at least one species of
fly, the Tachinid Phryxe vulgaris,
which also attacks several other species of caterpillar, including
Small Tortoiseshell.
Orange tip
larvae are noted for their cannibalistic tendencies - this
may have evolved because
some of the larval foodplants ( e.g.
cuckoo flower ) only produce enough seed pods
and foliage to sustain a single
larva through to full development. Larvae are very reluctant to leave the
plants on which they hatch, so for their own survival it becomes
necessary for them to devour their competing brethren.
Caterpillars
which have been feeding on cuckoo flower leave the plants
when ready to pupate, and attach themselves with a silken girdle
to a nearby woody stem. Larvae on garlic mustard however
usually pupate on the stems of the plant.
The distinctive
boomerang-shaped pupa cannot be mistaken for any other species.
It occurs in two colour forms -
pale green, or
brownish. The
latter is by far the commoner. In 2009,
I made a quick search of a clump of garlic mustard in a Sussex
woodland, and found 5 pupae, of which 4 were the normal brownish
form, and one of the green form. One pupa was parasitised, another
had been nibbled by a small mammal ( probably a pigmy shrew ), and
the remainder were healthy. All were attached to the stems of dead
garlic mustard plants.
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Orange tip Anthocharis cardamines,
pupa ( normal form ) on garlic mustard stem |
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Orange tip Anthocharis cardamines,
pupa ( green form ) on garlic mustard stem |
Adult behaviour
Male Orange tips begin emerging in early April, followed about a
week later by the females. As with many other butterfly species,
female Orange tips must mate within a couple of days of emergence,
after which they appear to lose their attraction to the males, so
the staggered emergence is nature's way of ensuring that there are
plenty of males available when the females emerge.
When seen in flight, female Orange tips
can be
difficult to distinguish from Green-veined
Whites, but when they settle, the beautiful mottled green markings
on the underside hindwings make them easy to identify. The
green
colour is
actually an illusion
caused by a mottling of black and yellow scales. The markings are
an extremely effective camouflage which works against a variety of
backgrounds - the butterflies are
equally
difficult to spot
when
at rest on bracken fronds, hazel leaves,
or
nettles;
or
on the white flowers of garlic mustard or umbellifers.
Orange tips visit a wide variety of
wild
flowers including bluebell,
bugle, wood anemone, blackthorn, primrose, ground ivy, celandine, hawthorn, garlic
mustard, early purple orchid,
common vetch, dog violet, colt's foot, dandelion
and
cuckoo flower.
When nectaring or settling for short periods, they normally keep
their wings half open. This has the effect of trapping a tiny
pocket of warm air over the thorax, and thereby aids rapid body
warming. In hazy weather or late evening
sunshine
however
they often
bask for long periods with the wings
fully outspread.
Orange tip Anthocharis cardamines,
male on cuckoo flower, Dunsfold, Surrey
Males patrol constantly in search of females, and when the sexes
meet copulation takes place immediately, without any prenuptial
ritual. If a female that has already mated is intercepted by a
male, she
signals her disinterest to his advances by settling on a
leaf, flattening her wings and raising her abdomen. This tells the
male that she is unreceptive, and makes it physically impossible
for him to copulate.
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Anthocharis cardamines,
female ( right ) raising her abdomen as a signal to the male that she is
unreceptive to his advances. Magdalen Hill Down, Hampshire. |
Orange tips roost
openly, even in wet or windy weather, and can be found at dusk and
dawn settled on the flower heads of cuckoo flower, garlic mustard,
bluebells and hazel or nettle leaves, in sheltered and lightly wooded
situations.
Orange tip Anthocharis cardamines,
female at roost on hazel, Stansted Forest, Sussex
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