In order to complete a holocycle of the green peach aphid, Myzus persicae, on a synthetic diet, the effects of dietary amino acid contents on development of sexuals were investigated. For this purpose, the aphids were reared on holidic diets for two to three generations at 20°C under a scotophase of 15 h per diem. Under these conditions, the production of males by the aphids on a synthetic diet was very much poorer than those reared on radish seedling. On reducing the amino acid concentration of the diet, the proportion of males produced was comparable to that produced by aphids fed on radish seedlings. The obtained males were smaller and survived longer than those reared on radish seedling. Under the long night photoperiod and on the synthetic diet with reduced amino acids, gynoparae and then oviparae were also obtained. The oviparae were mated with the males grown on the synthetic diet, and laid eggs. The eggs, however, did not turn dark in color, and perished. 01 1995 WiIey-Liss, Inc.