Residual activity of methoxyfenozide (Intrepid) against the southwestern corn borer, Diatraea grandiosella Dyar, and sugarcane borer, D. saccharalis (F.), was assessed on corn plants under field condition during 2004. Early tassel stage corn plants were treated with methoxyfenozide at concentrations of 70 to 140 g(AI)/Ha.. Five to ten neonates of each species were released in the collar of the leaf directly above or below the uppermost ear. Larvae were infected at 3, 7, 10, 14, 17, and 21 days after insecticide application. Number of plants with entrance/exit holes, bored shanks, or lodged stalks, and seed yield will be recorded at harvest time to determine the duration of the residual activity of the insecticide against the two major corn pests in Louisiana.