The cotton leafworm, Spodoptera littoralis (Boisd.) (Noctuide : Lepidoptera) was reared on two artificial diets (kidney bean and broad bean) and natural diet comparable with feeding on (castor oil bean leaves) under laboratory conditions at.  27±1°C and 70±5% R.H. The biological aspects were evaluted thorough eight generations. The two artificial diets  were more preferred to the insect than the natural diet . The results revealed  that the mean weight of the larval instars of S. Littoralis reared on the diets were significantly higher than that reared on the natural diet  . The deposited eggs per female  were slightly higher on artifical diet  than those laid on natural diet. Moreover, the duration of generations were affected by the rearing on the two diets (33 and 32 days), respectively, while not affected when rearing on the castor oil bean leaves (42 days). Larval stage duration was significantly higher when reared on board bean than rearing on the castor oil bean leaves. The adult females of  longevity was 7, 9 and 6 when feeding on kidney bean, broad bean and castor oil bean leaves, respectively. It be concluded that brood bean diet is the best to conduct out the different bio assays for the cotton leafworm , S littoralis