The comparative toxicity of two Emamectin benzoate [(Speedo5.7% WG) and (Basha 1.9% EC)], two Lambdacyhalothrin [(Bestend 10% WP) and (Max sped 5% EC)] were examined against the cotton leafworm Spodoptera littoralis (Boisd.) 4^th larval stage   on castor bean leaves. The effect of rate spreading droplets on the toxicity of Emamectin benzoate and Lambdacyhalothrin formulations were investigated under laboratory conditions. The results showed that Lambdacyhalothrin (Max sped 5%Ec) exhibited the highest toxicity against the fourth larval stage of S. littoralis with LC₅₀values of 0.007 ppm. In contrast, Lambdacyhalothrin,( Bestend 10% WP) had the lowest toxicity with LC₅₀values of 0.033 ppm.  On the other hand, the Emamectin benzoate (Speedo5.7% WG) was given the lowest LC₅₀ value of 0.0061 ppm   followed by (Basha 1.9% EC) LC₅₀ value of 0.0097 ppm. The results of joint toxic effect between rate spreading droplets and insecticides indicated that Emulsifiable concentrate of Lambdacyhalothrin and Emamectin benzoate formulation was the highest both rate spreading droplets and the mortality rates