Common Blue (Polyommatus icarus)

/ / Terrestrial Inverts


Polyommatus icarus is closely related to the P. coridon and P. bellargusP. icarus is a small (28 to 36 mm) butterfly (1). The male upper sides are an iridescent lilac blue with a thin black border (2).  Females are brown with a row of red spots along the edge of their wings (1). They usually have some blue at the base of the wings. Undersides have a greyish brown colour in the males and more brownish in the females (2). The caterpillars are small, pale green with yellow stripes.

Life Cycle

Eggs are laid singly on young shoots of their food plants (1).  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 (1). The larvae creates a substance called honey dew, which the ants eat while the butterfly lives in the ant hill.  Its flight time is between May and September (1).


Its habitat include a range of grassland habitats such as: meadows, coastal dunes, woodland clearings and also many man made habitats, including roadside verges and waste ground (1).


It is widespread throughout Europe, North Africa and temperate Asia (2).


The main food plant is Bird’s foot trefoil (Lotus corniculatus). Other plants consumed include Medick lupulina, Ononis repens, Trifolium repens and Trifolium dubium (1).


Description written by Lilli Lehtinen (2009)

(1)   Butterfly Conservation (2009) Common Blue (Male) [online] Available: [date accessed: 21/05/2009]

(2)   UK Butterflies (2008) Common Blue [online] Available: [date accessed: 21/05/2009]