Hexane extract of Porteresia coarctata (Roxb.) exhibits a toxic effect on the tissues of Spodoptera litura (F) while fed at the dose of 1000 and 2000 ppm thoroughly mixing with castor leaves (Ricinus communis L) after dissolving in DMSO at late fourth instar whereas only DMSO treated castor leaves were fed to control group. The larvae were put to rear at $28^{circ}C{pm}1^{circ}C$, $76{pm}4%$ R.H. under 12 L + 12 D photoperiodic regime. In test group insects substantial reduction of protein and DNA content was marked in fat body and midgut tissues compared to DMSO treated control group. The significant biochemical alterations in the midgut tissues and fat body of test group insects indicate the insecticidal property of the said plant extract that could be tested in facilitating the phenomenal stride in Integrated Pest Management.