Insects provide a source of natural compounds that may have therapeutic benefits on many diseases including cancer. The present study aimed at investigating the cytotoxic activity of red palm weevil, Rhynchophorus ferrugineus and Egyptian cotton leaf worm, Spodoptera littoralis larval extract against adenocarcinoma-Breast cancer (MDA), Hepatocellular carcinoma (HepG2), and Normal cell line (Wi38), as well as High -performance liquid chromatography (HPLC) analysis of tested extracts. The extraction was carried out using n-butanol solvent. Generally, a comparison of cytotoxicity against MDA and HepG2 cancer cell lines with the Wi38 cell line, showed that the viability of fibroblast was higher than cancer cells after treated with n-butanol extract from R. ferrugineus and S. littoralis larvae different concentrations and have less cytotoxicity on fibroblast than cancer cell lines, it means that their side effects are low. The R. ferrugineus and S. littoralis larval n-butanol extracts recorded IC₅₀ values of 315.17 and 188.78 µg/ml against Wi38; 81.19 and 96.55 µg/ml against MDA; 49 and 92.78 µg/ml against HepG2, respectively. Also, the HPLC analysis of n-butanol extract from R. ferrugineus and S. littoralis larvae revealed the presence of chlorogenic acid, catechin, and gallic acid with a moderate concentration, as well as methyl gallate, ellagic acid, ferulic acid and quercetin within the extracts, making substantial contributions to the therapeutic properties of tested extracts.