Antimoultant insecticides, Alsystin and Dimilin 25% W.p. which inhibit chitin sythesis in insects were tried against 2nd and 3rd instar larvae of shisham defoliator, Plecaptera refexa Guen. (Notodontidae). Both the chemicals in laboratory as well as field trials, in doses of o.02 and 0.04% concentrations gave cent percent mortality of the larvae. The residual effect of the insecticides continued up to about one month and provided cover for two successive and overlapping generations the non-target insects, which do not feed in foliage were absolutely safe from the adverse effect of the chemicals.