Abstract: The objective of this study was to characterize the control efficacy of two formulations of Nosema Iocustae against grasshoppers in surrounding area of Qinghai Lake of Qinghai Province. The results showed that at the 30~ day post-application of the two formulations of Nosema Iocustae, the control efficacy was above 70%. It is indicated that when the population density of grasshoppers is in a moderate or lower level, an obvious control efficacy can be obtained with the the two formulations of Nosema Iocustae in the year of application.