Proceedings of the final research co-ordination meeting organized by the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Phoenix, Arizona, 9–13 September 1991. Genetic control of lepidopterous pests includes the environmentally benign use of the sterile insect technique as well as the use of inherited sterility, which is especially pronounced in the first filial (F1) generation following the exposure of the parents to substerilizing doses of ionizing radiation. In the case of inherited sterility, the F1 generation is reared in the field, thereby reducing costs. Some lepidopterous species can be mass reared in factories, stockpiled in diapause, irradiated and activated for release in synchrony with the wild population. This method has been highly successful since 1968 in protecting 0.5 million hectares of cotton in the San Joaquin Valley of California from the pink bollworm. This report presents information mainly on the inital phases in the development of the use of inherited sterility to manage populations of the corn earworm, codling moth, Asian corn borer, European corn borer, diamondback moth, cotton leafworm, fall army worm, tropical army worm, gypsy moth, pink bollworm and wild mulberry silkworm.