Some responses were observed in the eggs and larvae of Spodoptera littoralis (Boisd.) under different concentrations of V. lecanii. The fungus proved virulent against the two stages of the insect. Treatment of the eggs appeared more susceptible to fungi than larvae. The treated eggs appeared a high reduced rate of hatchability and most of the hatched larvae from treated eggs failed to develop to adults and dead. LC50 for eggs was 1.15 x 107 spores/ml, and for larvae was 1.55 x 107 spores/ml. The obtained results from this work will be make it possible useful and promising potential of V. lecanii to be considered as a biocontrol agent against the S. littoralis.