Language: English with bilingual keys in English and Japanese
Forty-nine species of the genus Cosmopterix of Japan are revised. The author proposes a tentative phylogenetic system of the Japanese members of the genus using the morphological characters of adults and larvae, and the ecological characters of the larvae. He describes twenty-ﬁve new species together with a redescription of one species unrecorded from Japan and twenty-three previously known species. In the classiﬁcation of these species of Cosmopterix the author gives species-group names for some species.