The Sugarcane Aphid, Melanaphis sacchari, is a major worldwide crop pest causing direct feeding damage on sorghum and transmitting viruses to sugarcane. In the US, Mexico and Caribbean, an invasive genotype of Sugarcane Aphid has become a major pest of sorghum since 2013. The taxonomic status of M. sacchari varies among authors. Some consider that the species M. sorghi is a synonym of M. sacchari, while others consider them as distinct species according to morphological differentiations. In this study, based on the comparison of samples collected from the whole distribution area, we use both morphometric and molecular data to confirm that M. sacchari and M. sorghi are distinct species. The invasive genotype recently introduced in the Americas is found to be M. sorghi.