postman

The postman butterfly is predominately black with either red or yellow bands across the forewings. The postman butterfly has large long wings (35–39 mm). It is poisonous, and the red patterns on its wings are an example of aposematism. They look similar to H. erato. Two features found on the underside of the hind wings help to distinguish H. erato from H. melpomene—H. erato usually has four red dots where the wing attaches to the thorax while H. melpomene usually has three. In Mexico, Central America and the west coast of Colombia and Ecuador, the yellowish-white stripe on the underside reaches the margin of the hindwing in H. erato but ends before reaching the margin in H. melpomene. There are many geographical races/subspecies/morphs of this butterfly throughout Central and South America. The geographical variation in patterns has been studied using linkage mapping and it has been found that the patterns are associated with a small number of genetic loci called genomic "hotspots". Hotspot loci for color patterning have been found homologous between co-mimics H. erato and H. melpomene, strengthening evidence for parallel evolution between the two species, across morph patterns.

Heliconius melpomene is found from Central America to South America, especially on the slopes of the Andes mountains. It most commonly inhabits open terrain and forest edges, although it can also be found near the edges of rivers and streams. It shares its range with other Heliconius species, and H. melpomene is usually less abundant than other species.

Unlike most other butterflies, several Heliconius species have been observed eating pollen as well as nectar. The exact mechanism by which the butterfly digests the pollen is uncertain; it was originally thought that once the pollen was soaked in nectar after ingestion, it would then be able to be digested by the butterfly. Recently, however, the enzyme protease was discovered in the butterfly's saliva, which implies an adaptation for breaking down pollen. This enzyme was found in higher concentrations in the saliva of female butterflies, likely due to the greater need of nutrition associated with reproduction. These adaptations allow the butterflies to extract important amino acids from the pollen, which, in addition to general nutrition benefits, allows H. melpomene to have brighter colors and be more distasteful to predators than their non-pollen-foraging counterparts. It is thought that this foraging adaptation and subsequent enhancement of coloration contributed to the speciation of Heliconius.