Water hyacinth, Eichhornia crassipes, is considered as the worst aquatic plant in the world that causes a serious hazard to nation's developmental activities. The present study was planned to explore the potential of E. crassipes by making its positive attributes outweigh the negative ones. Thus, the present study was carried out to disclose to the effect of E. crassipes extracts "extracted by different solvents pet.ether, acetone and ethanol" and kingbocommercial formulations of plant extract on 4^th larval instar of Spodoptera littoralis. Some biological aspects were recorded. Also, the phytochemical scanning was carried out to E. crassipes extract. In addition, the efficiency and residual effects of kingbo against S. littoralis under field conditions were also investigated.        Obtained results revealed that the percentage of larval mortality was increased with increasing the concentrations of all tested compounds. It also showed that all tested compounds caused reduction in pupal weigh compared with control. Results showed that, sterols/terpenoid and flavonoids were the most constitute of E. crassipes. In addition, the present findings showed inhibition effect on total protein content except petroleum ether extract which clarify non significant effect on 6^th instar larval haemolymph. Also, in Esterases pattern were differed than the normal pattern.