Toxicity and histological effects of two essential oils (Peppermint oil and Eugenol) and two insecticides (Chlorpyrifos and Chlorfenapyr) in nano and traditional EC formulations have been tested against 4^th instar larvae of Spodoptera littoralis.The results revealed that nano emulsion exhibited considerable toxic activities against the laboratory strain of cotton leafworm. Using bioassay test, showed that the nano-emulsion of chlorpyrifos was 10.33 times more than traditional EC emulsion followed by nano chlorfenapyr was 2.77 times more than traditional emulsion. On the other hand, the nano-emulsion of peppermint oil was affected 2.54 times more than traditional EC emulsion while, nano eugenol was 1.55 times more than traditional emulsion in nano and traditional formulations. Histological studies in the midgut of 4^th instar larvae treated with LC₅₀ concentration of the tested compounds showed great destruction compared with untreated larvae. Our results indicated that the nano formula of essential oils and two tested insecticides were more effective against S. littoralis than commercial formulation. nano forms of essential oils (peppermint oil, eugenol), and insecticides (chlorfenapyr, and chlorpyrifos) exhibited histopathological studies in the midgut of S. littoralis.