The effect of the sublethal concentrations of acetone extract of Piper cubeba fruits ,acetone and petroleum ether extracts of Thymus vulgar& flowering buds ,malathion and pirimiphos-methyl on some biological aspects of T. castaneum survivors was studied in the laboratory at 30 f 2^°C and 70 ± 5% R. H. The results showed that all treatments decreased significantly the number of eggs laid daily per femal during two weeks by 64.6, 51.2, 32.5, 39.0 and 27.8 % for the a forementioned treatments, respectively. On the other hand, no significant differences were achieved between all treatments and control for eggs hatchability, duration of pupal stage and sex ratio. The preoviposition period was prolonged significantly with P. cubeba acetone extract., while, it deceased obviously with Thymus vulgar& acetone extract. The incubation period of eggs was increased significantly with P. cubeba, but it reduced significantly with Thymus v4aris petroleum ether extract. Duration of larval stage and total developmental period of immature stages were significantly decreased by using the sublethal concentrations of T vu/garisacetone extract, malathion and pirimiphos-methyl.