This study was conducted to identify the susceptible stages of the cotton leafworm, Spodoptera littoralis to the entomopathogens fungus, Metarhizum anisopliae and bacterium, Pseudomonas aeuriginosa. The mortality percentages recorded after treatment of the 2^nd and 4^th instar larvae of S. littoralis with concentration 1×10⁸ spore/ml of M. anisopliae were 84.28 and 75.71% after 5 days of treatment. While, LT₅₀ were 0.81 and 1.93 days for 2^nd and 4^th instar larvae of S. littoralis, respectively. P. aeruginosa concentration 2.3× 10⁸ spore/ml caused mortality 81.42 and 60% and LT₅₀ 3.87 and 4.51 days for 2^nd and 4^th instar larvae of S. littoralis, respectively. Pupae of S. littoralis were susceptible for both entomopathogens agents. Moreover adults emergence percentage decreased. Combined treatment of pesticides with P. aeruginosa and M. anisopliae proved best action causing higher mortality percentages for larvae compared with using pesticides alone.