The effect of radiation dose and different release ratios of treated (T) to untreated (U) Cryptophlebia leucotreta (Meyrick) (Lepidoptera: Tortricidae), on the incidence of fruit damage, the competitiveness of the treated males, and population growth was examined inside field cages. Navel orange trees were individually enclosed in large nylon mesh cages. Newly emerged adult moths treated with either 150 or 200 Gy of gamma radiation were released into the cages at ratios of 5T:1U or 10T:1U. The fruit was collected after 4 wk, and the number of damaged fruit and larval entries per cage were recorded for each treatment. Infested fruit was maintained in the laboratory until all emerging F₁ progeny were collected and outcrossed to untreated moths of the opposite sex. Treatment had a significant effect on the mean number of larval entries and on the number of undamaged fruit per cage. The number of larval entries as well as the number of F₁ progeny per cage decreased as the overflooding ratio increased. A significant reduction in egg hatch was observed in the progeny of crosses between F₁ females or F₁ males originating from the treatment cages compared with crosses of F₁ moths originating from the control cages. The lowest mean number of fertile F₁ adult females and males was obtained from the 150 Gy and 10T:1U ratio treatment. This treatment also showed the lowest per generation rate of increase (<1 from the parental [P₁] to the F₁ generation), suggesting that growth in the fertile population would have been prevented if releases of treated moths at this dose and ratio were maintained in the field.