Application of plant compounds for agricultural pest control, specially stored product pests, were common from many years ago in various countries. Various species of plants in some rang-lands of Iran are known to have anti-insect properties. Evaluation of these plant extracts for their effects on the pests and determining their chemical compounds, are needed for their application in pest control. In order to evaluate insecticidal potential of herbal extracts a factorial experiment of completely randomized design with three replications on Callosobruchus maculatus was adopted for a pilot experiment in the laboratory. These plant extracts were prepared from 22 plants with three solvents (Methanol, Acetone and N-Hexane) with 30% concentration. Experiments were carried out in petri dishes, at 25?C and 70 ± 5% RH under dark conditions and mortality were recorded after 24 and 36 hours. In this experiment, each plant extract that had caused more than 50% mortality on C. maculates was selected for further laboratory screening. Each unit of experiment in pilot test consisted of a petri dish covered with a filter paper and 1.5 ml of each treatment solution was poured in it and 25 insects were released into them. In this stage of experiment methanolic leaf extract of Teucrium polium (with 55.04 percent mortality), hexane extract of Sonchus oleraceus (with 54.64 percent mortality), acetonic leaf extract of Calotropis procera (with 53.6 percent mortality), methanolic extract of Fumaria parviflora (with 52.7 percent mortality), methanolic extract of Capsicum annuum (with 50.04 percent mortality), acetonic extract of Thymus vulgaris (with 50 percent mortality) and acetonic extract of Origanum vulgare (with 49.21 percent mortality) were selected. After carring out the pilot experiment, the effective extracts with five concentrations of 15, 22.4, 33.5, 50.2 and 75% and one control were evaluated on the C. maculates. This experiment was designed as a factorial experiment of completely randomized design with three replications and mortality was recorded after 24 and 36 hours. On the basis of this experiment, in the highest concentration (75%), extract of Fumaria parviflora and extract of Thymus vulgaris (with 88.3% mortality) had higher mortality and extract of Sonchus oleraceus (with 78.3%) had lower percentage of mortality. The LC50 values of effective extracts were calculated for C. maculates after 36 hours of treatment with plant extracts. The results showed that C. maculates with LC50 = 126.27 µl/ml has higher sensitivity against extract of Fumaria parviflora and has lower sensitivity against extract of Sonchus oleraceus with LC50 = 370.09 µl/ml in comparison to other extracts This insect showed moderate sensitivity to other extracts