The Cairns birdwing, Ornithoptera priamus euphorion, is found along
the east coast of north Queensland. The adults are usually found along
the edges of rainforest, but can also be found in the cities wherever
their food plant has been introduced. Eggs are laid singly, usually on
the underside of leaves of a vine, Aristolochia tagala. The caterpillars
hatch after about a week and start eating. Every few days they shed
their skins, growing rapidly for five or six weeks. The plant they feed on
is poisonous, which gives them protection from predators. They also
have a structure called an osmaterium. This is a pair of red fleshy horns
just behind the head which the caterpillar everts when alarmed. It stinks
of the foodplant and is a reminder of its poisonous nature.
When they are ready to pupate they wander off and may attach
themselves to either a leaf or branch. The pupa, or chrysalis, is an
intermediate stage in which the tissues of the caterpillar are broken
down and reformed into butterfly tissues. The adult butterflies emerge
early in the mornings so they can take full advantage of the tropical day.
Mating will take place within a few hours, and may last for some time.
When they separate, the male will seek out other females. The female
looks for the foodplant to lay her eggs.