When they are ready to pupate, Cairns Birdwing caterpillars drop off the Aristolochia vine they had been eating and climb a neighbouring plant. There they find an appropriate twig or leaf, reinforce it with some of their silk, make a sling with more silk, and hang there in their new hard brown skin (which is what the chrysalis is) while they miraculously re-organise inside it (see this blog post for more details). When the time comes …
