This large, striking, black-and-white butterfly is also known as the rice-paper butterfly, perhaps because of the unusual texture of the wings, but also perhaps because the way it flits and floats in the air is said to be like a piece of paper drifting in the wind. Another name is the paper-kite butterfly. It is a giant insect, the largest butterfly in Japan, with a wingspan of 95 to 110 mm. The black spots along the bottom edges of the wings are unevenly joined together, as are the spots just above them, giving the wings a ragged, striped appearance. The chrysalis is yellow with black marks. The base of the wings, where they join the thorax, are tinted yellow. The front legs, should you get close enough to notice, are short and brush-like and useless for walking. They have club-shaped antennae.
Where to find them:
This animal is probably most likely to be seen in butterfly parks and farms, where it is a popular insect. The tree nymph is attracted to the color red, and will land on red shirts and hats. In the wild it can be seen from Kyushu to Okinawa, in fields and woodland. It is also seen across Southeast Asia.
These butterflies seek out lianes and vines, and milkweed, which are all creeping plants that grow around trees. Many of these plants contain bitter-tasting alkaloids, and it is thought that the female locates the correct plants to lay her eggs on by smelling out the alkaloids.
The plant alkaloids apparently have a similar structure to the male pheromones of this butterfly, so it appears that there has been an ancient evolutionarily relationship between the butterfly and its food plant. Probably the alkaloids evolved first, and male nymph butterflies evolved to have similar-smelling pheromones. Alkaloids in plants that the butterfly does not feed on are completely unlike the male pheromone. The caterpillars accumulate the bitter alkaloids in their bodies, protecting them from predation. The alkaloids remain in the insect's tissue even when it transforms into an adult. Through literally bitter experience, predators learn to avoid both the caterpillars and the adults.