Effects of high temperatures on development and fecundity were examined using Aulacorthum solani（Kaltenbach）and Aphis glycines Matsumura clones. Nymphs of all A. solani clones showed 100% mortality at 30°C. By contrast, all nymphs of three A. glycines clones out of four survived and became adults at 30°C. The numbers of nymphs produced by adult females of A. solani clones were higher at 20°C than at 28°C. Adult females of A. glycines clones produced more nymphs at 28°C than at 20°C. These results suggest that A. solani is more susceptible to high temperatures rather than A. glycines.