Effect of diatomaceous earth (DE) on mortality of adults of  Sitophilus oryzae clearly revealed the importance of temperature and relative humidity. Hundred per cent mortality was recorded at combinations of  highest temperature (350C) with all the four relative humidities of 30, 50, 70 and 90 per cent and at 300C in only 30, 50 and 70 per cent relative humidity combination. While, at 250C, at only two lower relative humidities (30 and 50%) and at lowest temperature 200C in only with lowest relative humidity (30%) combination. However, in other combinations mortality ranged from 75 to 97 per cent. Very similar trend have been observed in two releases. Seed germination ranged from 38 to 88.5 per cent in different concentrations of temperature and rh tested. Least germination was recorded in untreated control (40 %). No seed damage was recorded even at highest rh (90%) at both highest temperature (30 and 35oC). More seed damage (52.25%) was noticed in untreated control.