Crambus lathoniellus is a species of moth of the family Crambidae described by Johann Leopold Theodor Friedrich Zincken in 1817. It is found in Europe, Central and South-East Asia.
The wingspan is about . In this Crambus a white longitudinal stripe emanates From the wing base ending sharply at an obliquely running dark line. In some specimens a white spot is formed in continuation and up to the submarginal line. The longitudinal strip has behind the center (seen from the base), closer to the submarginal line a "tooth" facing outwards and to the inner edge. Meyrick - Forewings with apex somewhat produced ; brown, sometimes ochreous-mixed, in male with grey, in female with whitish blackish-edged interneural streaks; a subcostal white streak on basal half; a white median streak, upper edge straight, lower edge projecting in middle, cut by sharply angulated dark brown median line ; second line angulated, white, edged with dark brown, preceded by white costal mark ; a white terminal streak, with several black dots ; cilia metallic. Hindwings rather dark grey. Larva greenish-grey or brownish-grey ; dots darker ; head brown, darker-marked: in silken galleries above or among roots of grasses.
The moth flies from May to September depending on the location.
The larvae feed on various grasses.