SMALL POSTMAN. Adult nymphalid of the Heliconius erato species, picture taken in the butterfly greenhouse, the Yvelines, France. As numerous species of the Heliconius genus, this butterfly is toxic. The larvae feed on a toxic plant of the Passiflora genus for which they are immuned. So, the adult butterflies have accumulated the toxic substances in their body. The characteritic colors that they bear enable the predators to recognize them and do not approach them. Heliconius erato Small Postman