Abstract: Having studied on long-term regular occurrence patterns of main insect pests oncrops such as Mythimna separata Walker, Nilaparvata lugens StOl, Cnaphalocrocis medihalls Guenee, Chilo suppressalis Walker, Tryporyza incertulas Walker, Schizaphisgraminum Rondani, Ostrinia furnacalis Guenee and Helicoverpar arrnigera Hiibner etc.,it was discovered that the periodicity of pest occurrence for M. separata, C. suppressalis,N. lugens, C. medinalis and O. furnacalis was 16 years approximately. A periodicity of about 12 years also occurred in N. lugens, T. incertulas. An approximately 11 years periodicity for C. suppressalis, C. medinalis, S. graminum and H. armigera was found.A forecast of the trend of the pests for 1996-2000 years is presented.

Key words: forecast, insect pest, statistics