A study of the gross effects of gamma radiation on the Indian-meal moth, Plodia interpunctella (Hübner), and the Angoumois grain moth, Sitotroga cerealella (Olivier), was conducted. All metamorphic stages of the insects were treated with 13.2±10%, 17.5, 25, 45, or 100 kilorads of gamma radiation. Weekly observations were made to check mortality, ability of treated metamorphic stages to continue their development, and reproduction by treated individuals and their first-generation progeny. Eggs of both species and larvae of the Indian-meal moth were effectively controlled by all dosages. Larvae of the Angoumois grain moth were controlled by all dosages except 13.2±10% kilorads, which permitted, some lanvae to develop to the adult stage and reproduce. The life of insects treated as adults or as pupae was not greatly shortened by the treatments, but the incidence of sterility and a marked reductiou in progeny produced per pair of moths varied directly with the dosage applied. Genetic damage, as evidenced by reduced reproduction, was transmitted to the F1 generation. When treated directly, males of both species were less subject to genetic damage than Were females; however, the progeny of treated males was more subject to genetic damage than was the progeny of treated females.