Greenbug, Schizaphis graminum (Rondani), (Hemiptera: Aphididae) is a major insect pest of cereal grains on the southern Great Plains of the United States. This chapter summarizes greenbug life history and biology, provides a description of the direct and indirect crop injury caused by greenbug to wheat and sorghum, and reviews current research efforts concerning greenbug management including biological control, cultural control focusing on host plant resistance, monitoring, and chemical control that can be incorporated into an IPM program.