Toxicity of six materials, two plant essential oil (clove and flax seed oil), two plant extracts (neem and harmal seed extracts) and two inorganic salts (silica dust and tri-calcium phosphate) mixed with wheat grains at different concentrations against granary weevil was studied. Based on LC₅₀, LC₉₀, both lower and upper values of confidence limits as well as slope values of LCP lines for the six materials, the obtained results indicated, in general, that these compounds could be arranged according to their effectiveness at all tested concentrations as follows: clove oil > flax seed oil > silica dust > tri-calcium phosphate > neem seed extract > harmal seed extract.