The current study was conducted to determine the insecticidal activity of essential oils (EOs) of three plants : Anethum graveolens, Thymus vulgaris and Myristica fragrans on economic grain pest, Tribolium castaneum Herbst (Coleoptera : Tenebrionidae) and Oryzaephilus surinamensis Linnaeus (Coleoptera : Silvanidae). GC-MS analysis showed that EOs had the major constituents of dillapiole (44.01%), estragole (15.30%) and safrole (14.93%). Results of fumigant assays showed that A. graveolens had the highest insecticidal activity against T. castaneum and O. surinamensis adults with LC50 values of 76.12 and 80.60 µl/l air, respectively, followed by T. vulgaris and M. fragrans. However, it was the lowest effective oil with LC50 values of 105.70 and 128.87 µl/l air to T. castaneum and O. surinamensis, respectively. When EOs tested for their effect to markedly kill the tested insects showed that A. graveolens killed faster than T. vulgaris and M. fragrans. It could be concluded that A. graveolens EO had potential against T. castaneum and O. surinamensis compared with T. vulgaris and M. fragrans which might be recommended as grain protestants’ in grain stores against stored insects