Full-grown pupae Agrotis ipsilon were irradiated with 5 or 10 krad and crossed with unirradiated female. The F1 progeny were more sterile than parents. Percentage of mated female of F1 was greatly reduced while the mating frequency was increased. Less inseminated females were among the F1, particularly when the female inherited the sterility. The mortality among larvae of the F1 was high and dose-dependent, and that among F2 larvae was even higher. The sex ratio of the F1 progeny was altered in favour of male, while that of the F2 was normal. 10 krad for P1 male was sufficient to inhibit hatching of the eggs produced by F1 adults.
