Eggs ofLissorhoptrus oryzophilusKuschel were exposed in the laboratory to constant water temperatures of 25°, 30°, 35°, and 40°C. None hatched at the high temperature. The average number of days to hatch were 9, 6, and 4 when exposed to the 3 lower constant temperatures, respectively. The response of eggs of different ages held at 25°C but exposed to 45°C for different periods of time indicated little mortality resulted from 1–3-h exposure. Mortality occurred when eggs were exposed to 45°C for 6, 9, or 15 h, but eggs midway in their development seemed more tolerant than 2–3 day old eggs or those in the last stages of development. The rate of development was slower by ca. 1 day when eggs were exposed to 45°C, regardless of the time of exposure.