Heliconius ethilla, the ethilia longwing, is a butterfly of the family Nymphalidae. It was described by Jean-Baptiste Godart in 1819. It is found from Panama to southern Brazil. The habitat consists of marginal forests. The wingspan is 60–70 mm. The forewings are orange with a black margin and four black spots. The hindwings are orange with two black stripes. The larvae feed on Passiflora species. Full-grown larvae have a white body with an orange head and reach a length of about 17 mm.