Common Blue

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Common Blue
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Lepidoptera
Superfamily:	Papilionoidea
Family:	Lycaenidae
Subfamily:	Polyommatinae
Tribe:	Polyommatini
Genus:	Polyommatus
Species:	P. icarus
Binomial name
Polyommatus icarus (Rottemburg, 1775)

The Common Blue (Polyommatus icarus) is a small butterfly in the family Lycaenidae.

Appearance, behaviour and distribution

Male uppersides are an iridescent lilac blue with a thin black border. Females are brown with a row of red spots along the edges. They usually have some blue at the base of the wings and, especially in Ireland and Scotland, are mostly blue but always have the red spots. Undersides have a greyish ground colour in the males and more brownish in the females. Both sexes have a row of red spots along the edge of the hindwings (extending onto the forewings though generally fainter, particularly in the males where they are sometimes missing altogether). There are about a dozen black centered white spots on the hind wings, nine on the forwings. The white fringe on the outer edge of the wings is not crossed with black lines as it is in the Chalkhill and Adonis Blues, an important difference when separating these species, particularly the females.

It is Britain's (and probably Europe's) most common and most widespread blue, found as far north as Orkney and on most of the Outer Hebrides. Males are often very obvious as they defend territories against rivals and search out the more reclusive females. A range of grassland habitats are used: meadows, coastal dunes, woodland clearings and also many man made habitats, anywhere where their food plants are found.

It is widespread in Europe, North Africa and temperate Asia.

Recently, Polyommatus icarus was discovered in Mirabel, Quebec, Canada by Ara Sarafian. An amateur entomologist, he had been observing the butterfly from 2005 to 2008. He contacted the Canadian National Collection of Insects in Ottawa where the butterfly was identified as P. icarus, a new alien butterfly to Canada and North America. The butterfly seems to be well established and is extending its range from year to year (Source: http://www.entsocont.com/Newsletter_Dec_2007.pdf).

Lifecycle and food plants

The main food plant on most sites is Bird's foot trefoil (Lotus corniculatus). Others used include Black Medick Medicago lupulina, Common Restharrow Ononis repens, White Clover Trifolium repens and Lesser Trefoil Trifolium dubium. Eggs are laid singly on young shoots of their food plants.

The caterpillar is small, pale green with yellow stripes and as usual with lycid larvae rather slug-like. Hibernation occurs as a half grown larvae. They are attractive to ants but not as much as some other species of blues. The chrysalis is olive green/brown and formed on the ground where it is attended by ants which will often take it into their nests. The larvae creates a substance called honey dew, which the ants eat while the butterfly lives in the ant hill. In the south of Britain there are two broods a year flying in May and June and again in August and September. Northern England has one brood flying between June and September. In a long warm year there is sometimes a partial third brood in the south flying into October.

Gallery

Female Common Blue	Male Common Blue, northern Norway	Female Common Blue
Male (underside)	Close-up	Two consume feces

Lifestyle

• Diet, caterpillars: leaves of plants.
• Diet, Butterflies: wildflower nectar.
• Lifespan: 3 weeks as butterfly.

See also

Wikimedia Commons has media related to: Polyommatus icarus

• List of butterflies of Great Britain