The rates of development of larvae and pupae of the waxmoth,Galleria mellonella, and its nuclear polyhedrosis virus (Baculovirus) were determined over a range of temperature from 18°–40°C. Larvae did not undergo significant development at 18°C and virus disease was slowed but not inhibited. At 40°C, both larval development and virus disease were stopped. Upon return to a lower temperature, larvae resumed development but the degree of disease development depended upon the time of exposure to the high temperature.