Overuse of synthetic pesticides causes problems for humans and the environment or leads to insect resistance to insecticides, so plant extracts and essential oils have gained popularity as an environmentally acceptable alternative to chemical pesticides. This study investigated the toxicity of Delonix regia leaf and seed extracts, protein patterns, and genetic distance analysis against the 5th instar larvae of cotton leafworm, Spodoptera littoralis Boisaduval. Methanol, petroleum ether, and acetone extracts of leaves and seeds of D. regia were used to coat castor leaves for ingestion by the 5th instar of S. littoralis larvae. The seeds' methanol and petroleum ether extracts were the most effective (100 and 98 Mortality%), with LC