[Objective] This study aimed at revealing the effect of insecticide spray on the infestation level of rice planthopper in large spatial scale and in long term. [Method] The data set included twenty counties from 1991 to 2009. Therefore fixed effect model was established to evaluate the effect of insecticide spray on the infes- tation level of rice planthopper. The OLS method was used to estimate the fixed ef- fect model. [Result] The regression results of the fixed effect model suggested that one period lag insecticide spray had a significant effect on the infestation level of rice planthopper. [Conclusion] Even though rice planthopper is a migratory rice pest, insecticide spray has a significant effect on the infestation level of rice planthopper in large spatial scale and in long term.
