The effects of various exposure to irradiation from cesium 137 in nitrogen and air on survival and fecundity of Glossina palpalis palpalis were compared. With doses from 3 to 21 krad in nitrogen atmosphere, male fertility was inversely correlated with dose, above 15 krad male survival was inversely correlated with dose. All males subjected to either 21 krad in nitrogen or 15 krad in air were sterilized. Females appeared to be more sensitive to gamma-irradiation than males; a dose of 6 krad in nitrogen resulted in 100% sterility and arrested further development of the ovaries after the ovulation of follicles A1 and C1. In males, this dose caused 70.3% sterility. Approximately 97 and 98% sterility were obtained when males were treated with 15 krad in nitrogen and 12 krad in air respectively. No fly emerged from irradiated puparia younger than 15 days. Irradiation of 15 or 20 days old puparia killed the insect either before or shortly after eclosion, whereas the normal patterns of emergence, survival and reproduction were observed from puparia that were irradiated when 25 days old or older.
