Samples of wheat containing rice weevils, Sitophilus oryzae (L.), and lesser grain borers, Rhyzopertha dominica (F.), of known age were exposed to temperatures of 39 plus/minus 1 C with relative humidities ranging from 75 to 50% during a 4-day adult ovipositional period, and a continuous exposure to 39 plus/minus 1 C and 60% for the rice weevil and at 43.3 plus/minus 1 C with a relative humidity of 50% for the lesser grain borer.