This distinction is the basis for the earliest taxonomic divisions in the Lepidoptera - the Rhopalocera ( `` clubbed horn '' , the butterflies ) and the Heterocera ( `` varied horn '' , the moths ) . This distinction is the basis for the earliest taxonomic divisions in the Lepidoptera : the Rhopalocera ( `` clubbed horn '' , the butterflies ) and the Heterocera ( `` varied horn '' , the moths ) .