The Common Blue is a small butterfly, not as common as its name implies, but found on open grassland, where its favourite flowers, Marjoram and Fleabane, are found. It is very variable in colour, the males being blue with a white fringe, with a black pencil line separating the two colours, sometimes with the black veins bleeding into the white, with pale blue shining veins. The female is duller, with bluish or brownish wings and an edging of orange and white spots.
The larva is bright green with darker lines, and a black head. Larval foodplants include Bird's Foot Trefoil, Restharrow and Clover.
The underside is pale bluish to grey, with orange, black and white spots and speckles.
