This study aimed to evaluate the bioactivity of the essential oil of basil leaves, Ocimum basilicum on newly hatched larvae of Spodoptera littoralis. The chemical composition of the basil oil using (GC-Ms) analysis showed Linalool (48.26%), Eucalyptol (9.21%) and Estragole (5.16%) as the major constituents. Results indicated that the basil oil has larvicidal activity against S. littoralis . Latent effects with LC₅₀ value of basil oil on the successive stages were also detected, both larval and pupal duration was significantly elongated as compared to control, while the reverse was true in case of pupation and pupal weight. Additionally, the tested essential oil caused significant inhibition of the activity of acetylcholine esterase enzyme and significant increase in Lactate dehydrogenase enzyme than control.