The Geometrid moth genus Erilophodes Warren was redefined, using morphological characters of the wings, abdomen, hind tibiae and genitalia. Two new species, E. Spinosa and E. toddi, were described on the basis of male characteristics. Females of these species are indistinguishable from each other and from those of E. colorata Warren, the type species. Ischnopterix Wagneri Le Moult was treated as a junior subjective synonym of E. colorata Warren. Three species referred to Erilophodes Warren were removed from the genus. E. indistincta Warren was transferred to the genus Ischnopterix Hubner. E. marmorinata Bastelberger was placed as a junior subjective synonym of Neodesmodes semialbata Warren. E. arana (Dognin) was transferred to the genus Neodesmodes Warren. Erilophodes Warren was found to occupy an area from Espirito Santo on the southern coast of Brazil to Montevideo, Uruguay, westward through the northeastern tip of Argentina into southeastern Paraguay. There seems to be considerable overlap in the ranges of the three species. Placement of Erilophodes Warren in the subfamily Ennominae was verified. With some reservations the genus was retained in the tribe Nacophorini. / Master of Science