Samples of wheat containing mature larvae and early pupae of the rice weevil, Sitophilus oryzae (L.), aged 15-18 days were continuously exposed to constant temperatures of 27.5, 30.0, 32.5, or 35 plus/minus 1 C and 60% RH. Only 52% of the F1 adults survived the 7-day ovipositional period and emerged from the infested wheat. No F2 progeny emerged after exposure to 35 plus/minus 1 C.