Linear regression and multiple regression stepwise selection procedure analyses were used to relate population fluctuations of bean leaf beetle, Cerotoma trifurcata (Förster), in soybean, Glycine max (L.) Merrill, to climatic factors. The study was conducted at Iowa State University Johnson farm near Ames, Iowa for 10 consecutive years (1989 through 1998, inclusively). Bean leaf beetle adults were sampled twice weekly from emergence to mature stages of soybean. Linear regression showed a strong relationship between first- and second-generation adult densities during the growing season, whereas multiple regression analyses indicated a high correlation between second-generation adult densities and environmental factors, including temperature and precipitation. The analyses demonstrated that field history of beetle density is important for pest management. The major factors that affected the population dynamics of bean leaf beetle and regression models for the beetle density prediction are discussed.