Temperature plays a critical role in the population dynamics of insects. This study was designed to estimate the effect of exposure of Frankliniella occidentalis (Pergande) in the parental generation to 41 °C for various durations (2, 6, 12, 24, and 36 h) on their reproduction and on the first generation progeny. The data indicated that, under both the arrhenotoky and the sexual reproduction pattern, the longevity of adult females and the numbers of larvae and adults in the first generation decreased significantly as the period of exposure to heat increased. When adults were exposed at least 24 hours under arrhenotoky and at least 6 hours under sexual reproduction, the total survival rate from larva to adult in the first progeny generation was significantly lower compared with control groups whose parents had not been exposed to heat treatments. Furthermore, high-temperature exposure of sexually reproducing adults significantly decreased the proportion of females in the first progeny generation: The sex ratio (♀:♂) changed from 2.69:1 in the control to 2.31:1 after 2 h to 2.14:1 after 36 h of heat treatment. These results support the hypothesis that heat stress could be of use in the control of the western flower thrips.