Effects of ozone (O₃) stress of potato, Solanum tuberosum L., on fecundity, larval growth and survival of Colorado potato beetles, Leptinotarsa decemlineata (Say), were measured in greenhouse and field experiments. Chronic O₃ exposure caused moderate to severe foliar injury on an O₃-sensitive cultivar (‘Red Norland’) but caused only minor injury an O₃-resistant cultivar (‘Superior’). Foliar injury caused by O₃ was greater on old than on young leaves but feeding by adult beetles was greater on young leaves in all experiments. Foliar analyses of the five uppermost leaves (nodes 1–5) showed higher carbon (C) and higher nitrogen (N) concentration in Superior than in Norland. There were no significant O₃ effects on C or N and no cultivar × O₃ interactions. Egg production by newly emerged adult beetles feeding on plants exposed to high O₃ levels was not significantly different from egg production on plants exposed to low O₃ levels, regardless of cultivar O₃ sensitivity. Feeding and energy conversion efficiency of neonates and survival of larvae to the adult stage were not significantly affected by the O₃ treatment. Although present levels of tropospheric O₃ are high enough to significantly affect yield of sensitive potato cultivars, our results indicate no significant effect of ambient O₃ concentrations on Colorado potato beetle populations.