In the present study, 42 pure monoterpenes and volatile aromatic compounds were tested to evaluate their toxicities against adults of granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae) at laboratory condition. For the insecticidal activity tests, 10 and 20 mu L/Petri dish concentrations for liquid compounds and 10 and 20 mu g/Petri dish concentrations for solid compounds were used. The results show that majority of tested compounds were found to be toxic against to the adults of S. granarius and they showed various degrees of toxicity with range of 6-100% mortality. Among the compounds tested, oxygenated monoterpenes, linalool, carvacrol, terpinen-4-ol, limonene oxide, carvone, dihydrocarvone, fenchone, menthone and aromatic volatiles, p-anis aldehyde, benzyl acetate, cinnamyl aldehyde in the current study displayed complete mortality on the pest adults after 24h of exposure. In general, oxygenated monoterpenes and aromatic compounds exhibited high toxicity as compared with monoterpene hydrocarbons. Among the monoterpenes hydrocarbons, the highest toxic effects were shown by gamma-terpinene, limonene and beta-pinene. Our results showed that linalool, carvacrol, terpinen-4-ol, limonene oxide, carvone, dihydrocarvone, fenchone, menthone, p-anisaldehyde, benzyl acetate and cinnamyl aldehyde were the most toxic compounds against the adults of the pest. Therefore, these compounds can be used as natural insecticides against the S. garanarius adults.