Insect pests cause economic damage to cereals in both quality and quantity. The objective of the current study was to assess the contact, fumigant toxicity and repellent activities of Citrullus colocynthis L. essential oil (EO) alone, contact activity of DE and the combined effect of EO with various concentrations of Diatomaceous earth DE against the adults of Sitophilus oryzae L., Oryzaephlius surinamensis (L) Stegobium paniceum (L) and Tribolium castaneum (Herbst.) under laboratory conditions. The obtained results indicated that mortality rates of insects were positively affected by increasing both of concentration and the exposure time. The fumigant toxicity of C. colocynthis was higher than the contact toxicity whereas at 120 h post treatment the LC50 was 2.64, 4.61, 13.4 and 17.32 ml/l for S. oryzae, O. surinamensis, S. paniceum and T. castaneum respectively, while in the contact case it was 3.92, 12.6, 36.7 and 48.86 ml/l, respectively. Strong repellent of C. colocynthis achived 100, 95.5, 98.8 and 86.6% after 12 hours for S. oryzae, O. surinamensis, S. paniceum and T. castaneum, respectively at 20 nL/c𝑚𝟐. Diatomaceous earth achieved strong contact toxicity whereas at 168 h post-treatment LC50 values was 2.287, 2.63, 5.40 and 20.2 % (w/w) for S. oryzae, O. surinamensis, S. paniceum and T. castaneum, respectively. Based on the obtained results, S. oryzae was the most susceptible species, whereas T. castaneum was the most tolerant ones. The essential oil C. colocynthis has the ability to be utilized as one of the integrated stored product pest management programs.