The mature larva of Dynastor napoleon Doubleday (Lepidoptera: Nymphalidae: Brassolinae) is described from material reared in southern Brazil on a large bromeliad species in the family Bromeliaceae. The larva is dull green, with lighter-green spined bumps across the entire surface and a series of beige/dark brown mid-dorsal spots, one at each intersegmental junction. The bifed tails are long. On each side the highly patterned head has four knobbed, dark brown horns.