Grain in bins or ear corn in storage has small buff moths flying about the bins or cramling rapidly over the surface of the grain when it is disturbed. One or two small round holes are eaten in the kernels of infested corn or in other grain. This insect is the most destructive grain moth occurring in our country casing great damage to corn in cribs and also destroying ripening grain, especially wheat, in the field. The present study deals with the effects of gamma irradiation on the different developmental stages of the angoumois grain moth sitotroga cerealella (olivier) with special reference to the effects of sterilizing dosage on sexual competition. 15 tabs., 9 figs., 116 refs.