Chalkhill Blue

The male Chalkhill Blue has pale silvery-blue upper wings with thin dark edges, while the females are chocolate brown with orange spots around the edges. The undersides of the wings in both males and females show a pattern of white spots with black centres and orange crescent shapes on a grey-brown background. This butterfly is larger than many similar blue butterflies, with a wingspan of up to 40 millimetres. It is found only in chalky grasslands in southern England, especially on chalk downs and limestone hills from Dorset to Kent. The colonies are very localised and depend closely on their caterpillars’ food plant, horseshoe vetch. Adults appear from late July to early September and have just one generation each year. Males gather openly on bare ground and on flowers, particularly knapweeds and scabious. The species has a special relationship with red ants, which look after the caterpillars and pupae. In return, the ants receive sugary secretions from the larvae.