A study was carried out to evaluate the effect of temperature on the growth of the malathion susceptible strain, URY-O normal genotype and insecticide resistant strain, O-RY abnormal genotype, and ABURABI normal genotype of green peach aphid [Myzus persicae]. The nymphal periods were not significantly different between URY-O and O-RY strains at 25°C. At 30°C, susceptible strain URY-O could give birth to offspring almost normally, while resistant strain O-RY could not produce any offspring for 20 days which resulted in nymphal death. The numbers of offspring of strain URY-O and strain ABURABI were not different between 25°C and 28°C, but strain O-RY, when it was reared at 28°C, could produce offspring only at a rate of 10% of those at 25°C. Body weight of strain URY-O and strain ABURABI were 0.22 mg/female and 0.27 mg/female, respectively at 28°C, however that of O-RY was only 0.16 mg/female, showing considerable difference between normal and abnormal genotype. Substrain O-RY(+) which has high esterase activity showed poor reproduction ability(0.8 progenies per G1 individual) compared with substrain O-RY(-) (3.4 progenies per G1 individual) which has low esterase activity at 28°C.