The rice weevil, Sitophilus oryzae(L.) (Curculionidae) (Coleoptera) and the
red flour beetle, Tribolium castaneum (Herbst) (Tenebrionidae) (Coleoptera) are the most important insect pests that attack grain during storage. Thus, the use of chemical pesticides in combating these insects caused serious damage to humans and the environment. The current study aimed to test one of the relatively safe pesticide alternatives, which is plant oils. In current study, the efficiency of nutmeg oil, watercress, cinnamon and parsley was evaluated through fumigation method, as well as studying the effect on the biology of S.oryzae and T.castaneum, in addition to study the effect on weight loss. Results showed superiority of cinnamon oil over other oils against T. castaneum and parsley oil on S. oryzae. In general, these oils reduced the number of offspring of T. castaneum, with values ranging from 7.33 to 100, as well as the offspring of S.oryzae, from 62.89 to 100.