Cupido decolorata

 Cupido decolorata, the Eastern short-tailed blue, is a small butterfly found in the Palearctic (Albania, Austria, Bulgaria, Hungary, Greece, Spain, Romania, Slovakia and the Soviet Union - the European part, the Czech Republic, Yugoslavia, Russian Federation) that belongs to the lycaenids or blues family.

Description
It is a small butterfly with a sexual dimorphism, the upperside of the male is dull blue bordered with grey, that of the female is brown, both with a white fringe. The underside is pale grey a little suffused with blue and decorated with lines of small black dots.This species is similar to the Short-tailed blue (Everes argiades) and to Cupido alcetas.

Biology
The larva on feeds on Medicago sativa,  Medicago lupulina