A method for screening seedling and older rice plants for resistance toMythimna separata(Walker) andSpodoptera mauritia acronyctoides(Guenee) was developed. In all seedling stage tests, many entries were readily fed upon, and when the most susceptible entries were consumed, the nonpreferred varieties were also heavily damaged. The most resistant varieties in the seedling stage were those belonging to the wild rice groups, especially group II, which has a different genomic constitution thanOryza sativa.In tests involving older plants, IR20, IR46, and B-441-B-126-1-2-3 were heavily damaged when infested with 2nd- and 3rd-instar larvae