The responses of adult femaleHypothenemus hampeiresistant and susceptible to endosulfan were compared using a vapour exposure method at five temperatures, from 22°C to 34°C, for up to 10 h. Susceptible insects showed a rapid increase in mortality 2–4 h after exposure to concentrations above 100 ppm. Resistant insects were largely unaffected at all combinations of temperature and exposure time. The LC50of susceptibles declined with temperature, indicating a positive temperature coefficient. The method is recommended for early and reliable detection of endosulfan resistance after 6 h, at 25°C, with a concentration of 400 ppm.