Catharylla serrabonita is a moth of the Crambidae family. It is found in Brazil (Bahia, Espirito Santo). The length of the forewings is 10–14 mm for males and 14 mm for females. The costal line on the forewings is ochreous and the median transverse line is ochreous to brown. The subterminal transverse line is ochreous to brown. The hindwings are cream-coloured, usually with more or less connected marginal brown spots.