Heraclides thoas, Rio Claro, Colombia – Adrian Hoskins
Introduction
The subfamily Papilioninae comprises about 550 species of worldwide distribution, and includes the Swallowtails, and the Dragontails and giant Birdwings of south-east Asia. Heraclides thoas is distributed from Mexico to Bolivia and Argentina, and occurs as a rare stray in the southern United States.
Habitats
This species is migratory in nature and found in many different habitats including tropical rainforest, cloud forest, humid deciduous forest, orchards, and suburban zones at altitudes between sea level and about 1600m.
Lifecycle
The eggs are laid singly on leaves and stems of the larval food plants, or on nearby plants, along forest edges, roadsides, and riverbanks. The larvae feed primarily on Piper, but also possibly on Zanthoxylum, Citrus, and Ptelea, although larvae found on these plants are more likely to be the very closely related cresphontes.
The young thoas larva is dull in color, and similar in appearance to a bird dropping. In common with other Papilionidae larvae, it is equipped with an extrusible forked appendage – the osmaterium, which is situated behind the head. This is everted if the larva is molested, and gives off a noxious pheromone containing isobutyric acid, which is believed to be used as a defense against ants. When fully grown, the larva loses the warty tubercles and becomes pale green, with extensive areas of white on the thoracic and anal segments.
Adult
The adult is black, marked with broken bands of cream, and has fluted tails on the hindwings. It is extremely similar in appearance to Heraclides cresphontes, and can only be distinguished from it with certainty by examination of the abdominal tip. H. cresphontes, however, has a more northerly distribution, being found from Canada to Colombia.
Heraclides thoas, Satipo, Peru – Adrian Hoskins