The upperside of the male's wings are pale violet blue, whereas the females have varying amounts of brown and blue. Both sexes have pale brown underwings with variable spotting.
Wingspan 29 - 38mm.
Ova are laid on bird's foot trefoil and other Leguminosae. Larvae overwinter in lower stems of foodplant or in ground litter, and recommence feeding in April. Generally single brooded in north, although in exceptional years there may be two broods. Two sightings of fresh specimens occurred in October 2005, one in Culbin Forest, the other in Strathconnon, suggesting a second brood (see Branch Newsletter 11).
June to August.
Found throughout the mainland area, the Western Isles and Orkney. Has also been recorded in Shetland.