Abstract. Aphids formerly regarded as Euceraphis punctipennis (Zetterstedt) are distinguished as two species, E.punctipennis and E.betulae (Koch), on the basis of cytological and morphological differences. E.punctipennis is primarily associated with Betula pubescens Ehrh., and E. betulae with B.pendula Roth. Seasonal variations in morphometrics, pigmentation and development of wax glands in the two species are described and compared. A key to European and North American species of Euceraphis is provided.