Cosmopterix dulcivora is a moth of the family Cosmopterigidae. It is known from China (Jiangxi), Japan, Fiji, Samoa, the Philippines (Negros), Java, Australia (Queensland), and Russia.
The length of the forewings is about 5 mm. The larvae have been recorded feeding on Poaceae species, including Miscanthus sinensis in Japan and Saccharum officinarum in Fiji, the Philippines and Queensland.