Cupido decolorata Cupido decolorata, the Eastern short-tailed blue, is a small butterfly found in the Palearctic that belongs to the lycaenids or blues family.DescriptionIt 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 and to Cupido alcetas.BiologyThe larva on feeds on Medicago sativa, ''Medicago lupulina''