The present work aimed to study the toxic and antifeeding activities of certain plant extracts against Spodoptera littoralis (Boisd.) The extracts of lantana and lemongrass leaves were applied at 5 & 10% concentrations, against 2nd and 4th instars larvae of S. littoralis under laboratory conditions 27 ± 2 °C and 55 – 65% relative humidity. Results showed that the lemongrass extract in water at 10% conc. on the 2nd larval instar and lantana extract in water at 10% conc. on 4th larval instar were the highest in efficacy as antifeedants. Regarding, conversion of ingested and digested food (ECI) & (ECD) lantana extract in water 10% had the least effect. The highest mortality percentage was attained from the lemongrass extract in acetone 10% and lantana extract in water 5% treatments against both the 2nd and 4th larval instars, respectively. Data showed that all the plant extracts caused significant reductions in respect of larval and pupal durations, pupal weight and % of adult emergence compared with the untreated check. The plant extracts had a clear effect on the carbohydrates hydrolysis enzymes as amylase and trehalse