Pieris ergane, the mountain small white, is a butterfly of the family Pieridae.

It is found in Southern Europe, Asia Minor, Syria, Iraq, Iran and Transcaucasia.

(= narcaea Frr) (20 d), from South-East Europe and Asia Minor, is beneath devoid of black markings in male and female.

— longomaculata Rostagno is yellowish white above, the black spots of forewing are deeper in colour, larger, prolonged, the forewing beneath is straw- colour, with chrome -yellow apical spot, the hindwing beneath being also chrome -yellow.

semimaculata Rostagno the upperside of forewing, except the dark apical spot, is entirely white.