Managing stored-product insect pests by heating the ambient air of a food-processing facility to lethal temperatures is an old and effective technology. Temperature stratification during heat treatments may results in under-heated areas, which may cause survival of insects during heat treatment. The reproductive effects in insects surviving facility heat treatments are unknown. We simulated an under-heated environment in the laboratory by exposing 0-1-d old pupae and 2-wk-old adults of Tribolium castaneum (Herbst) at 50oC for median lethal time (LT50; 60 min for pupae and 39 min for adults). All possible reciprocal crosses were carried-out with treated insects and control (28oC) insects. Total number of eggs laid and egg-to-adult survival after two wk of pairing were determined. Total number of adult progeny produced at the end of two and eight wk periods was also recorded. The mean number of eggs laid by control female crossed with control male, treated in the pupal stage, was significantly higher (222.9 ± 12.8 eggs/female; n=3; at each n there were 15 subsamples), when compared with treated female crossed with treated male (80.9 ± 13.4 eggs/female). The adverse effect on the number of eggs laid was greater when pupae were treated when compared with adults. The total number of eggs laid was significantly higher when control female was crossed with control male (299.3 ± 6.2 eggs/female) when compared with treated female crossed with treated male (248.0 ± 15.8 eggs/female). Exposure to 50oC also affected egg-to-adult survival rate and F1 and F2 progeny production.