False codling moth, Cryptophlebia leucotreta (Meyrick), male and female mature pupae and newly emerged adults were treated with increasing doses of gamma radiation and either inbred or out-crossed with fertile counterparts. For newly emerged adults, there was no significant relationship between dose of radiation and insect fecundity when untreated females were mated to treated males (N♀ by T♂). However, fecundity of treated females mated to either untreated (T♀ by N♂) or treated males (T♀ by T♂) declined as the dose of radiation increased. A similar trend was observed when mature pupae were treated. The dose at which 100% sterility was achieved in treated females mated to untreated males (T♀ by N♂) for both adults and pupae was 200 Gy. In contrast, newly emerged adult males treated with 350 Gy still had a residual fertility of 5.2% when mated to untreated females, and newly emerged adult males that were treated as pupae had a residual fertility of 3.3%. Inherited effects resulting from irradiation of parental (P₁) males with selected doses of radiation were recorded for the F₁ generation. Decreased F₁ fecundity and fertility, increased F₁ mortality during development, and a significant shift in the F₁ sex ratio in favor of males was observed when increasing doses of radiation were applied to the P₁ males.