Butterflies of
Britain & Europe
Comma
Polygonia c-album
LINNAEUS, 1758
Family - NYMPHALIDAE
subfamily -
NYMPHALINAE
Tribe - NYMPHALINI
introduction
|
habitats |
lifecycle |
adult behaviour
|
 |
|
Comma
Polygonia c-album, male
hutchinsoni, Ballard Down, Dorset |
Introduction
The Comma
was regarded as a common species in the
18th century, but declined and became a great rarity between about
1850 and 1910. By 1930 it was on the verge of extinction, but then
it's fortunes suddenly changed. Thereafter numbers gradually
recovered, and the butterfly can currently be regarded as a common
species in southern Britain. In Hampshire and West Sussex for
example, it is certainly more abundant than either the Peacock or
the Small Tortoiseshell.
The butterfly
gets it's vernacular and species names from the C or comma-shaped
silver mark on the underside of the hindwings.
The generic name Polygonia is
a reference to the beautiful ragged wing shape. This is unique
among British butterflies, but there are several similar species
found elsewhere in the Holarctic region,
including the Southern Comma
P. egea of the Mediterranean area, and the
Question Marks and Angle-wings of North
America.
|
 |
|
Comma
Polygonia c-album, male at roost
on birch sapling, Stansted Forest, West Sussex |
The Comma is distributed across
most of Europe, but absent from Scotland, Ireland and northern
Scandinavia. Beyond Europe it occurs across temperate Asia to
northern China, Korea and Japan. It also occurs in Morocco,
Algeria and Tunisia.
|
 |
|
Comma
Polygonia c-album, male, March,
Stansted Forest, West Sussex |
|
 |
|
Comma
Polygonia c-album, f.
hutchinsoni, June, Stansted Forest, West Sussex |
Habitats
In spring
Commas breed primarily in woodland edge habitats where stinging nettles
grow in damp
but sunny situations, typically in glades or at the side of grassy
tracks.
The
summer adults are more mobile however, and can breed in
gardens, old quarries, along country lanes and railway cuttings, on
sheltered areas of scrubby grassland, and at coastal habitats. They roam freely
about the countryside and can be seen anywhere where stinging nettles grow, but
favour sunny sheltered sites with bramble bushes and a profusion of wild
flowers.
Lifecycle
There are 2
generations each year.
|
In February or March the butterflies awaken from hibernation.
Captive breeding experiments by L.W.Newman, and observations by
J.Thomas indicate that larvae hatching from the first few eggs
laid in early-mid March by overwintered females develop quickly.
Those that pupate before the summer solstice ( 21 June) ultimately
produce adults of the brightly marked hutchinsoni
brood, which emerges in early July. The progeny of these summer
adults produce another generation which typically emerges in late
August.
Meanwhile, the
remaining eggs, i.e. those laid by the overwintered females in
April and early May, develop much more slowly and produce adults
which emerge in early September, the result being that
butterflies of 2 different generations fly together in late
summer.
All of these butterflies emerging in late August and September,
regardless of parentage, are of the "normal"
form, with more angular wings and darker undersides.
In late
September or early October, the butterflies
of both broods
enter hibernation.
The hutchinsoni form is named after
Emma Hutchinson, who in the 19th century established that the
butterfly was double-brooded, and commercially bred the bright
summer form for sale to collectors.
|
The
green, ribbed eggs are laid singly, close to the edge on the upperside of
stinging nettle leaves. The butterflies typically
oviposit on nettles growing as small clumps in sunny
woodland glades, or sheltered by hedgerows. Egg-laying
sites are always close to nectar sources such as blackthorn ( in spring ) or
bramble blossom ( in summer ).
Two
hundred or so years ago the primary foodplant used in Britain by Commas was hop
Humulus lupulus, which was grown all over southern England as an
ingredient for ale.
The dramatic decline of the butterfly in
the late 19th and early 20th centuries is probably linked to changes of practice
which greatly reduced this formerly widespread and abundant plant. Fortunately
the Comma was able to adapt to making widespread use of another foodplant,
stinging nettle Urtica dioica and this has now undoubtedly
become the primary foodplant in Britain. Larvae are also found occasionally the
sucker growth of
English elm
Ulmus procera,
and more rarely on wych elm
U.
glabra,
sallow
Salix caprea,
hazel
Corylus avellana,
or cultivated blackcurrant
Ribes nigrum.
The
fully grown larva is unmistakable, being brownish black, with orange spikes on
the front segments, and a long splash of white along the back. It often rests on
the upper surface of a leaf, adopting a semi-curled posture, and at a glance can
be mistaken for a bird dropping.
The
chrysalis is marbled in shades of brown, decorated with small silver and gold
markings. Sometimes very dark pupae can be found, but these always turn out to
be parasitised. I have occasionally found pupae attached to concrete or wooden
fence posts, but at the woodland sites where the butterflies more generally
breed, they are more commonly found suspended from
woody stems or well shaded tree trunks.
|
 |
|
Comma
Polygonia c-album, Steyning, West Sussex |
Adult behaviour
In spring Commas occupy ride intersections and glades, and often
nectar at blackthorn blossom.
They also visit dandelions, cuckoo flower and hazel / sallow catkins.
They spend long periods basking on
the ground, on logs,
or
on bramble leaves or
dead bracken. It is also common to see them basking head-downward on fence posts, or
on the pale trunks of birch and ash trees.
Males occupy territories, and establish perches on twigs, or on a
favoured leaf, which act as vantage points. Intruding male Commas,
and butterflies of certain other species including Peacocks, are
always ousted by the "owner" of the territory. Summer brood Commas
often perch on hazel bushes or bracken, and intercept intruding
Gatekeepers and Speckled Woods.
Passing female
Commas
are intercepted, but I have never observed any courtship ritual,
or found any mated pairs. Copulation reportedly takes place high
in the tree tops.
Comma
Polygonia c-album, Stansted Forest, West Sussex
On warm sunny days in spring, butterflies
of both sexes
frequently settle on paths,
tree stumps or wood shavings
to imbibe
moisture.
Summer nectar sources include bramble, hemp agrimony, wild carrot,
marjoram,
thistles and
traveller's joy.
In early autumn the butterflies nectar at devil's
bit
scabious,
buddleia, fleabane
and ragwort; and often congregate to feed at fermenting
blackberries prior to hibernation.
Towards dusk
Commas seek overnight roosting sites. One evening in early July
2009, I
watched a female settling down to roost - she spent 2 or 3
minutes fluttering around on the shady side of an ivy covered
fence, and eventually settled for the night under an ivy leaf,
resting on the midrib, with head pointing towards the stem. On
several occasions I have found Commas roosting at ground level
among grasses - in these cases the butterflies always roost
head-downward. The camouflage is quite remarkable, giving the
impression of a dead oak leaf that has fallen onto the grass.
In
cool cloudy weather, Commas roost openly on foliage, and if
disturbed will feign death, falling to the ground, with their
wings closed, and their white legs tucked tightly against their
bodies.
|
 |
|
Comma
Polygonia c-album, July, Alice
Holt forest, Hampshire |
They spend the winter months hidden in wood stacks, hollow tree
trunks, or sometimes out in the open, hanging beneath branches.
The butterfly depicted below was found hibernating under a branch of
young coppiced sweet chestnut, about half a metre above ground
level in Stansted Forest. I found it on 26th January 2008 but
suspect that it had been hibernating there since the previous
October. It was still there in exactly the same position on 9th
February, but by 24th February had disappeared, presumably having
awoken from it's diapause with the arrival of sunny and slightly
warmer weather.
|
 |
|
Comma
Polygonia c-album, hibernating
openly under a low branch, January 2008. |
|
