Small Blue Butterfly (Cupido minimus)
This tiny blue butterfly is actually more brown than blue. although I'm not convinced!
Rare and localised, living in small sedentary colonies on sheltered chalky grasslands, this butterfly is still experiencing a decline in numbers and is a rightly, a priority species for conservation.
The larvae rely on kidney vetch as their sole food source although the adults also feed on Common Bird's-foot-trefoil and Horseshoe Vetch.
There's a section on this video which gives a good idea of just how small and difficult to find this species is:
That sedentary nature means individuals usually wander no more than approx. 40m from their birth place making it more difficult to encourage them to colonise new sites, although they may wander further on the hottest days.
The small blue is a butterfly in the family Lycaenidae. Despite its common name, it is not particularly blue. The male has some bluish suffusion at the base of its upper wings but is mostly dark brown like the female. The undersides are a silvery grey with small black dots. The male has a bluish tint at the base of its wings similar to the upper side.