It is a way of calling a group of insects, especially butterflies whose females have two distinct sexual openings. In Entomology it is the Castilianization of the name of a Clade or Division of the Lepidoptera Order (butterflies). The technical term is Ditrysia and means that it has two sexual openings (one for copulation and one for laying eggs). It includes almost all butterflies.
DITRISIOS: Branch of Lepidopterous Insects, without taxonomic rank, whose females have two sexual openings, for mating and egg-laying.