This butterfly is the commonest blue found in the British Isles. While the male has bright blue uppersides, the female is primarily brown, with a highly variable amount of blue.

This is the most widespread Lycaenid found in the British Isles and can be found almost anywhere. Good places to look for them in the valley are anywhere there is unimproved grassland. Bennerley, Shipley Country Park and Peewit Carr are good but this butterfly can appear in most habitats.

This species has 2 broods in our area, and 1 brood further north. There may be a 3rd brood in favourable years. Time of emergence is highly variable. In good years, adults may be seen as early as the middle of May on more southerly sites. These peak at the end of May, giving rise to a second generation that emerges in the second half of July, peaking in the middle of August.

The foodplants to look out for are Birds Foot Trefoil and White Clover.