In general, genitalic characters have been traditionally used for species identification in insects. Furthermore, comparative studies of male and female genitalia contribute with 50-100 % of the data used in morphology based phyogenetic analysis of butterflies in particular. Despite the obvious importance of this character system for butterfly research, little effort has been made by systematists towards standardized nomenclature, and comphehensive studies of character homology are lacking. Examples and possible solutions will be discussed regarding nomenclature and homology for the five butterfly families within Papilionoidea.