This work aims at evaluation the efficiency of the acetone and petroleum ether extracts of Cubeb fruits Piper cubeba (L.) and Thyme flowering buds Thymus vulgaris (L.) against the adults of Sitophilus oryzae (L.), Rhizopertha dominica (F.) and Tribolium castaneum (Herbst). Also, persistence of the two plant extracts compared to malathion and pirimiphos- methyl (actellic) using the most sensitive insect species (S. oryzae), was investigated .Results showed that , the efficiency of the two plant extracts was concentration and exposure period –dependent. At the highest tested concentrations (2&1%w/w), the acetone extract of P. cubeba and petroleum ether extract of T. vulgaris were highly effective against S. oryzae and R.dominica adults, while, T. castaneum adults were the least sensitive . On the other hand, the petroleum ether extract of P.cubeba and the acetone extract of T.vulgaris indicated lower effectiveness against the three tested insects even after two weeks from treatment. The results also showed that, malathion and pirimihos methyl indicated clearly longer residual toxicity than the two plant extracts.