This realm covers the Antilles and South America up to the border with the Nearctic realm (northern Mexico) and the Galapagos Islands. Most of this realm's surface lies in the tropical climate zone, with only the southern edges experiencing a temperate climate.

The Morpho ‘blue butterfly’ from South America is an example of structural colouration. Microscopic scales split light causing it to diffract. Some of the scattered light is absorbed so that we see only one particular colour, usually blue or green, and not all the colours of the rainbow. At rest or while foraging, these butterflies sit with their wings closed. A row of eyespots is visible on the lower part of the wings. They are useful for deterring enemies and for camouflage.

The Caligo is known as the owl butterfly because of the distinctive wing pattern reminiscent of an owl's eyes. This pattern is likely an example of mimicry, as it may resemble the eyes of some predators with large pupils and bright irises. Caligo are mostly found in forests, flying at dusk and in some cases also at dawn. Some species can be pests of banana crops in Central America.

Many species have almost completely transparent wings. The Caligo butterfly flies slowly; they are mostly found in tropical forests.