The larvae of this species feed on species of the Pararistolochia genus of vines.

Adult females will only lay about 27 eggs in their lifetime. The large sticky yellow-orange eggs are laid singly on the leaves of the host plant and hatch in around 13 days.

The larva feeds on the leaves of the host plant and goes through 6 instars in about 77 days. After this it will become a pupa in which it will spend 42 days before finally emerging as an adult.

Adult males have slender brown-black wings edged with vivid blue-green iridescent colouration. The abdomen is bright yellow.

The females, whilst larger, are drably coloured. The wings are more rounded and maintain the brown-black colouration. In place of iridescence the wings are marked with white/cream patches around the edges, and the abdomen is cream coloured.

Males may have a wingspan of up to 200mm, but the females can reach enormous proportions. One female specimen of O. alexandrae in the Natural History Museum has a wingspan of 273mm, making it not only the biggest specimen of this species in the world, but the biggest butterfly in the world.