Pupae of laboratory-rearedHaematobia irritans(L.) were irradiated with 2000 rad, packaged in a perforated styrofoam thermos, shipped on a commercial bus, and then released at the site of a pilot study of the sterile-male technique. Emergence of adults was reduced slightly by irradiation and significantly by shipment and release. Also, refrigeration of pupae to delay emergence of adults reduced percentage emergence (significantly when it was done before irradiation), and refrigeration for 48 h after day 7 reduced survival (significantly among irradiated males and normal females). More males than females emerged from all pupae, and significantly more (1.26:1) emerged from irradiated pupae held in the laboratory. Cross-mating studies demonstrated that all irradiated females were sterile, and only 2 of 7598 eggs hatched from normal females crossed with irradiated males. No significant difference was detected in the fecundity of normal females crossed with either normal or irradiated males.