This is the Spangle butterfly, Papilio protenor, is the latin name, and it belongs to the swallowtail family.
This picture was taken in Lion's Park, SaiKung. You can see pollen that has attached to its wings, so it is also acting as a pollinator.
Did you know: 1. Butterfly wings are transparent
A butterfly's wings are covered by thousands of tiny scales, and these scales reflect light in different colours. But underneath all of those scales, a butterfly wing is actually formed by layers of chitin, the same protein that makes up an insect's exoskeleton. These layers are so thin you can see right through them. As a butterfly ages, scales fall off the wings, leaving spots of transparency where the chitin layer is exposed.
2. Butterflies taste with their feet
Butterflies have taste receptors on their feet to help them find their host plants and locate food. A female butterfly lands on different plants, drumming the leaves with her feet until the plant releases its juices. Spines on the back of her legs have chemoreceptors that detect the right match of plant chemicals. When she has identified the right plant, she lays her eggs.