In fact, Yen even regards butterflies as types of moths. He explains that within the taxonomic structure used in the past, moths and butterflies were assigned to different sub-orders on the basis of individual characteristics such as differences in the morphology of their antennae. But in the taxonomy now widely accepted, the butterflies are assigned to various families in the Subsection Bombycina, on the basis of their general morphology and genetic characteristics.
他解釋，在過去的分類學架構下，依據蝶與蛾的單一特徵，例如觸角的差異，將蝴蝶與蛾分為不同亞目，但目前較合理且被廣泛接受的分類系統，卻根據它們的整體型態與分子特徵，將蝴蝶歸在蠶蛾亞群之下的各科裡。