The classification of the flower flies often referred to Syrphus s.l. has long been confused. European workers have usually placed all species in Syrphus or in Syrphus and Epistrophe; until 1950, American workers usually recognized the genera Syrphus, Metasyrphus, Epistrophe and Allograpta. Earlier attempts to revise the classification were in large part successful as far as many of the smaller, more distinctive groups of the tribe Syrphini were concerned, but Syrphus s.l. remained in a very unsatisfactory condition. In 1950 Fluke proposed a new classification of Syrphus s.l. based almost entirely on the male terminalia and treating particularly the New World species. It was a great advance on preceding attempts but left one large group in an unsatisfactory state. However, because no key to genera was provided, and because characters other than those of the terminalia were neglected, his arrangement was not generally accepted.