Fuscoptilia emarginatus is a moth of the family Pterophoridae. It is found in the Hokkaido, Honshu and Kyushu islands of Japan, the Kuril Islands, Korea, China and Amur. It is also known from Mongolia.
The length of the forewings is 8âÂÂ12 mm.
The larvae feed on Lespedeza bicolor and Lespedeza cuneata. The adult appears from May to September.