The effectiveness of mandarin crust oil, (Citrus reticulate) and Nano Chitosan was evaluated under laboratory conditions against egg masses, 2_nd instars larvae of cotton leaf worm, Spodoptera littoralis. The obtained results indicated that the effect of the oil and Nano Chitosan on S. littoralis eggs can be summarized as delayed embryonic development and ovicidal activity. According to the no hatchability % of the treated eggs, data showed that at the lowest concentration (10 ppm,1000ppm), (57%) of the Nano Chitosan, and mandarin crust oil caused a significant reduction in percent non hatchability compared with control (100 %). hatchability On the other hand, Nano Chitosan exhibited the highest toxic effect against egg stage followed by mandarin crust oil (Citrus reticulate) compared with control. However, the LC₅₀ values were 11.5393, and 550.423 ppm, respectively. The treatments showed toxic and morphogenetic effects on S. littoralis 2^nd instars larvae. Nano Chitosan was the most effective against 2^nd instars larvae of S.littoralis followed by mandarin crust oil. The LC₅₀ values were 6.537, and 2645.48 ppm, respectively. Also, the treatments were shown to cause some morphological changes in treated larvae. On the other hand, all treatments caused malformations in the emerged moths. So that, tested treatments can be applied safely in IPM program for the cotton leafworm, Spodoptera littoralis control.