The present investigation was carried out inAssiut Governorate to study the relative abundance of cereal aphid parasitoids and evaluate the host selection and host-instar preference of Schizaphis graminum (Rondani) and Rhopalosiphum padi L. by the braconid parasitoid, Diaeretiella rapae McIntosh during 2015 wheat growing season.The obtained results revealed that the dominance percentages of the pr...