The population dynamics of the green peach aphid (GPA),Myzus persicae(Sulzer), were examined on four commercial potato cultivars,Solanum tuberosum tuberosum(L.) cv. Katahdin, Norchip, Superior, and 8NW-8, with differing maturation rates and on one wild potato,S. canasensePI 283074. GPA abundance, population growth rate, alate abundance, and within-plant distribution were compared among cultivars. Results showed that GPA numbers were similar among commercial cultivars during most of the growing season. However, GPA population dynamics were influenced by potato plant phenology. GPA were more abundant earlier, populations peaked sooner, and declined earlier on the short-season cultivar, ‘Superior’. Populations on longer-season cultivars reached highest levels later. At 1,167 degree-days, GPA numbers were ca. 50% smaller on ‘Superior’ than on the mid-season cultivar, ‘Norchip’. Fewer GPA were observed onS. canasensethan on the commercial cultivars. GPA populations reached one-half their highest level from 6 to 8 days sooner in the growing season on ‘Superior’ than on later-maturing cultivars. Alate numbers were greatest on ‘Superior’, followed by ‘Norchip’, ‘Katahdin’, and 8NW-8. GPA were found predominantly on the lower leaves of each cultivar. GPA population growth rates were greatest on the lower leaves and slowest on the upper leaves of each cultivar. GPA populations increased more rapidly on the upper, middle, and lower leaves of ‘Superior’ than on longer-season cultivars.