Oncocera semirubella is a small moth of the family Pyralidae. It is found in Europe, including the British Isles. The wingspan is 26–30 mm. The adult moth flies in one generation from the end of June to August. It is easily disturbed from short grassland, flies from dusk onwards, and is attracted to light and sugar. The larvae feed on Lotus corniculatus, white clover, Ononis species, Horseshoe Vetch and Medicago species.