Mean development times of the Nantucket pine tip moth,Rhyacionia frustrana(Comstock), eggs and pupae were observed under laboratory conditions at nine constant temperatures (9 to 38°C). The development rate curves for eggs and pupae are the characteristic sigmoid shape of other insect development rate curves. The effect of humidity on the development time was relatively small compared with the effect of temperature. Egg and pupal mortalities were low at most temperatures within the range of development, with greater mortality near the upper and lower threshold temperatures. A larval development rate curve was estimated, using the temperature requirements of the tip moth life cycle under field conditions and the egg and pupal development rate curves.