Blueberry maggot, Rhagoletis mendax Curran, eggs and larvae infesting highbush ’Bluecrop’ and ’Elizabeth’ blueberries, Vaccinium corymbosum L. (Ericaceae), were treated with 4–1200 Gy of gamma radiation. The treatment reduced the number of immature stages that pupated and the number of adults that emerged from puparia. The lethal dose for 99.9968% mortality (LD 99.9968%) [lower and upper fiducial limits (FL)] estimated by linear regression analysis to stop pupariation was 1486 (1400–1585) Gy, at the 95% confidence level. The LD 99.99968% (lower and upper FL) estimated to stop flies emerging from puparia irradiated as immature stages was 88 (83–93) Gy, at the 95% confidence level as estimated by regression analysis. An estimated 100 762 larvae were killed, with no survivors, by irradiating 853 918 ’Bluecrop’ blueberries in bulk quantities with 71–776 Gy with a commercial irradiator. No flies or parasites emerged from puparia irradiated as larvae with ≥ 71 and > 80 Gy using commercial and research irradiators, respectively. Infestation rate of blueberry maggot larvae in nonirradiated ’Bluecrop’ and ’Elizabeth’ blueberries averaged 11.1 ± 1.2% and 14.3 ± 2.4%, respectively; the range of infestation rate was from 6.3% to 14.8% and 9.8% to 18%, respectively. Parasitism of blueberry maggot larvae by the larval–puparial parasite, Diachasmimorpha (Opius) mellea (Gahan) (Hymenoptera: Braconidae), averaged 10.1 ± 2.4% (range 3–13.3%).