The family Ethmiidae is represented in the Americas by 133 species, or about half the world fauna. A classification is proposed, based on correlation of a traditional biosystematic approach with a numerical phenetic analysis of adult characters. The 133 species are assigned to 3 previously existing genera; 49 species are described as new, 11 from Nearctic North America, 4 from the West Indies, 25 from Neotropical Mexico and Central America, and 9 from South America. Keys to the species are provided, based on external features of the moths. Literature synonymy, descriptions of morphological aspects, type data, geographical ranges, and flight periods are given for each species. All knowledge of geographical distribution patterns, behavior and biology, and morphology of the larva, pupa, and adult of the world ethmiid fauna is analyzed in development of speculation concerning the systematic position and phylogenetic relationships of these moths (see summary at end of text).
