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UK Nature  > Butterflies  > Polyommatus icarus

  • Female Common Blue
  • Close up of underside of wings

Scientific Name:   Polyommatus icarus
Common Name:   Common Blue

Polyommatus icarus, more commonly known as the Common Blue, has a wingspan of 2.7 - 3.4cm. The upperside of the male's wings are light blue with a violet tinge and a white fringe to the wing edges. The female has more brown, sometimes quite heavily overlaid with blue, with a row of orange spots along the outer wing-margins. Wing undersides are light grey in the males, light brown in the females, with a vivid pattern of dots in both sexes.

It is found throughout the UK, in dry and wet meadows and open, hilly countryside. The flight period is early April to mid-October, with two or three broods. Feeds at many flowers and at night rests head down on grass stems. Female lays eggs singly on the buds or flowers of the caterpillar's food plants. The caterpillar is pale green and woodlouse-shaped, with thin yellowish side stripes and short hairs.

Polyommatus icarus feeds especially on Bird's-foot Trefoil, but also on Lucerne, medicks, restharrows and other plants; frequently visited by ants which feed on secretions produced by glands at the hind end and protect it from enemies.
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