Insect growth regulators and plant extracts have an important effect on insects obviously on development and moulting process in different stages. Teflubenzuron (Nomolt) growth regulator and the plant extract Oxymatrine (Kingbo) were applied separately and together on Sesamia criticaLed. Nomolt gave the highest effect on adults and eggs and changed the behaviour of the adults in laying eggs in unusual places with lower hatching ratio. About its effect on the eggs, it caused decrease in hatching ratio and a higher mortality rate. When larvae developed into pupal stage; some of them formed in midi forms between larva and pupa then died, about those which lived up to the adult but in smaller sizes, less egg laying and less hatching than those treated with Kingbo, mixture or untreated. Kingbo has the least or almost no effect on adult behavior, hatchability of eggs also a very little effect on egg hatchability in eggs experiment. The application of the mixture of Nomolt and Kingbo resulted in an intermediate effect between each of them alone.