In this research, we applied integrative taxonomy approach in order to delimit species of Merodon caerulescens species complex. Molecular analyses confirmed COI sequence divergence between the Rhodes and Crete populations. Additionally, ITS2 sequences show certain differences which should be additionally tested. 28S rRNA gene sequences once again proved to be too conserved for closely related species delimitation. Geometric morphometry results indicate differences in wings shape between males and females of the two islands populations. Additionally, subtle differences between the two populations in the body coverage and colouration of hairs are also observed. Thus, based on the all presented evidence we concluded that taxon Merodon caerulescens is a complex of two species, M. caerulescens (Rhodes) and M. atricapillatus sp. n. (Crete).