The
common blue (
Polyommatus icarus) is a butterfly in the family
Lycaenidae. It has a
wingspan of 28 to 36 millimetres (1.1 to 1.4 in); the upper surface of the male's wings is an iridescent blue with a thin black border, while the female's wings are primarily brown, with a variable amount of blue. The underside has a greyish base colour in males and a more brownish hue in females. Common blues sequester
flavonoids from their host plants and allocate these
ultraviolet-absorbing pigments into their wings. Females do this more efficiently than males, and it is these pigments that attract males. This photograph shows a pair of mating common blues (male on the left, female on the right) in
Yoesden, a nature reserve in
Buckinghamshire, England.
Photograph credit: Charles J. Sharp