The present work aimed to study the effect of ethanol extract of Ricinus commnuis L. seeds on biological and physiological aspects for the cotton leafworm Spodoptera littoralis, 2^nd and 4^th instar larvae. The results cleared that the larval duration was 17.08 and 15.58 days & 10.11 and 9.36 days for treated and the untreated 2^nd & 4^th instar larvae respectively. The pupation percentage was 60.0 and 96.0 % for treated and untreated 2^nd instar larvae and 61.0 and 93.0 for treated and untreated 4^th instar larvae. The pupal weight was affected by the botanical extract. The pupal duration was 11.40 and 11.71 days for treated and untreated 2^nd instar larvae and it was 11.96 and 12.51 days for treated and untreated 4^th instar larvae. The emergence percentages resulted from treated 2^nd and 4^th instar larvae were 82.0 and 85.2 % compared with 97.0 % and 92.0 % for that resulted from the untreated larvae, respectively. On the other hand, the malformed adult was 28.0 and 2.0 % for 2^nd instar larvae (treated and untreated) and 16.0 and 5.0 % for 4^th instar larvae (treated and untreated) respectively. There are decreasing in fecundity of S. littoralis adults resulted from the treated 2^nd and 4^th instar larvae by the botanical extract used for this study. Effect of LC₅₀ value of the tested plant extract on the biochemical aspects of the 4^th larval instar of S. littoralis was detected. The biochemical aspects AST, ALT, alkaline and acid phosphatase activities, the as well as the total protein content post treatment of the 4^th instar larvae were considered throughout the present study.