A full consideration of the systematic position of Dacus armatus F. (the genotype of Dacus) and of Dacus bivittatus (Big.) is not attempted here, but it is necessary, owing to the economic importance of the latter, to clear up the confusion that has arisen between them. I am indebted to and thank Dr. A. J. Hesse, South African Museum, Capetown; Dr. John Smart, British Museum; Sir Guy A. K. Marshall, K.C.M.G., and Dr. F. van Emden, Imperial Institute of Entomology, and Dr. S. L.Tuxen, Zoological Museum, Copenhagen, for help in unravelling the problem.