New species of Cosmopterosis Amsel were discovered feeding on Capparis L. (Capparaceae) during exploration for caterpillars in the Area de Conservación Guanacaste (ACG), Costa Rica. Cosmopterosis is revised and now includes four species. Three new species, C. hispida, C. jasonhalli, and C. spatha, and the immatures of C. spatha and biology for two species, C. jasonhalli and C. spatha, are described; the type species, C. thetysalls (Walker), is redescribed. A key and illustrations for the identification of the species is provided. We propose a hypothesis for the relationship between species in Cosmopterosis and the placement of Cosmopterosis in the subfamily. The cladistic analysis, the first such analysis in the Glaphyriinae, included 21 morphological characters one of which, the radiodiscal process, a male secondary sexual character and presumably an androconial scent pouch is described and considered a autapomorphy for the genus. Male secondary sexual characters and larval feeding on Capparis in Pyraloidea and Lepidoptera is discussed.