Forty three European population samples of mealy aphids from various winter and summer host plants were attributed to respective species of Hyalopterus by means of their partial sequences of mitochondrial COI gene. Used Hyalopterus samples emerged as monophyletic relative to outgroup and formed three major clades representing three host specific mealy aphid species in the Neighbor joining, Maximum parsimony, Maximum likelihood and Bayesian inference trees. Hyalopterus pruni and Hyalopterus persikonus emerged as a sister species, whilst Hyalopterus amygdali was located basally. Samples representing different clades in the molecular trees were used for canonical discrimination analysis based on twenty two morphological characters. Length of the median dorsal head hair enabled a 97.3 % separation of Hyalopterus amygdali from the remaining two species. No single character enabled satisfactory discrimination between apterous viviparous females of Hyalopterus pruni and Hyalopterus persikonus . A modified key for the morphological identification of Hyalopterus species is suggested and their taxonomic status discussed. Keywords: Europe, Hyalopterus amygdali , Hyalopterus pruni , Hyalopterus persikonus , molecular phylogeny, mitochondrial COI, morphological key to species