The Chalkhill Blue butterfly, as its name indicates, likes chalk grassland. The male, above, has a pale blue topside with heavy black border, black spots on the hind wing edge and a white fringe. His underside is pale with the typical pattern of white-bordered black spots and orange and black edge spots.
The pale blue of the male fades with age, as does the black border.
The female topside is brown with orange "eyes" along the trailing edge of the hindwing. (The female Adonis Blue is similar, with blue scales instead of white in the "eyes".)
The female underside, above left and centre, is far darker than that of the male, above right.