Common blue

The Common Blue is a small butterfly in the family Lycaenidae, widespread over much of the Palaearctic and recently introduced in eastern Canada. Male uppersides are an iridescent lilac blue with a thin black border. Females are brown above with a row of red spots along the edges and usually some blue at the base of the wings; the upperside may be mostly blue, especially in Ireland and Scotland, but it always has red spots. Undersides have a greyish ground colour in the males and a more brownish in the females. Both sexes have a row of red spots along the edge of the hindwings and extending onto the forewings, though they are generally fainter there, particularly in the males, where they are sometimes missing altogether. There are about a dozen black-centered white spots on the hindwings, nine on the forewings. These usually include one in the middle of the forewing cell absent in Chapman's and Escher's Blues. 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.