Wheat at low temperatures was treated with hydrogen phosphide (PH3) ti control adult Tribolium castaneum (Herbst) and eggs and adults of Cryptolestes ferrugineus (Stephens). At temperatures of 8.5 to 11.3°C, a 100per thousand kill of adult. T. castaneum and C. ferrugineus was obtained when PH3 concentrations rose from 0 to more than 100 ppm in one day. There was also 100per thousand kill of adult C. ferrugineus when gas concentrations rose from 0 to more than 100 ppm during the course of 2 days. At these temperatures C. ferrugineus eggs survived gas concentrations which reached 900 ppm and then declined to 720 ppm during 4 days. The eggs also survived an exposure period of 7 days when gas concentration reached a maximum of 110 ppm on day 3 and then declined to 50 ppm on day 7. At temperatures of 1.1 to 7.2°C, a 100per thousand kill of adult C. ferugineus was obtained only after a 4-day exposure to PH3 though gas concentrations reached 540 ppm on day 4. At these temperatures C. ferrugineus eggs survived 7 days at gas concentrations which reached 520 ppm on day 4 and then declined to 400 ppm on day 7.