Margarosticha euprepialis is a moth in the Crambidae family. It was described by Hampson in 1917. It is found in Australia, where it has been recorded from Queensland, Western Australia and the Northern Territory. The wingspan is about 20 mm. The forewings have a pattern of orange with white markings outlined in dark brown. The hindwings are have a large area of black speckles, as well as black spots on the edges.