Another common name for the Psychidae is "case moths", but this is just as well used for the case-bearers (Coleophoridae). The names refer to the habits of caterpillars of these two families, which build small protective cases in which they can hide. The bagworms belong to the superfamily Tineoidea, which is a basal lineage of the Ditrysia (as is Gelechioidea, which includes case-bearers). This means that the bagworms and case-bearers are only as closely related to each other as either is to butterflies (Rhopalocera).