The genus Ethmia is included in the subfamily Ethmiinae, a subfamily composed of moderate-sized moths with a worldwide distribution (Powell 1973, 1985; Powell and Opler 2009). Recent molecular and morphological analyses place Ethmiinae within Depressariidae (Heikkilä et al 2013), though this subfamily has been previously treated as Elachistidae and so labeled in literature between 1999 and 2013.

Becker (1984) recorded 96 species of Neotropical Ethmia, distributed from Argentina to USA (Arizona and from Florida to Texas) and the Caribbean. Powell’s (1973) synoptic treatment of Ethmia of the same area recorded ten Costa Rican species. The national-level collecting during the last three decades by the Costa Rican Instituto Nacional de Biodiversidad (INBio) and the Lepidoptera inventory of Área de Conservación Guanacaste (ACG) in northwestern Costa Rica (Janzen et al 2009, Janzen and Hallwachs 2013) have generated additional life history information and resulted in the discovery of 35 additional Costa Rican species of Ethmia. We also have added DNA barcoding data to this new set of information, demonstrating its utility in disentangling species complexes first detected by Powell (1973). However, the Ethmia collection records for Costa Rica other than ACG are woefully few and hence not representative of the actually in-country distributions. Prior to DNA barcoding, which began in 2004, a large number of specimens collected during routine light trapping were ignored because it was assumed they were common, widespread species.

Worldwide information on the biology of Ethmia documents Boraginaceae as its most frequently used food plant family (Powell 1973, 1985; Powell and Opler 2009). However, caterpillar rearing by Janzen and Hallwachs (2013) in Costa Rica has discovered Gesneriaceae as an additional previously unknown food plant family.
(Phillips-Rodríguez et al., 2014)