Abstract: The present study was conducted to determine the duration of developmental stages of Callosobruchus chinensis and to identify the susceptible stages of azuki bean weevil to neem and sesame oils. The results of the study showed that the duration for the 1st to 4th instar larva and pupal stages of C. chinensis were 7-12, 12-16, 16-19, 19-22 and 22-27 days, respectively. The result showed that both the oils can control the larvae inside the bean cotyledons, indicating that the oils might penetrate into the cotyledons and chemically inhibit or kill the larvae inside the bean. It is concluded that earlier developmental stages were more susceptible than the later ones and the depth of the larval position in the bean and its tolerance might be responsible for the age-dependant effects of the oils.