The Papilio demodocus is also known as the Christmas butterfly or the citrus swallowtail. After the eggs of this butterfly hatch, the caterpillars which will emerge will feed on various plants such as citrus leaves and other plants from the Rutaceae family.
Souce: Wikipedia
Here is a rare photography of this Christmas butterfly in Mauritius just after its metamorphose. Leaving it's old envelope attached to the plant branch, it is now ready for its first flight. This butterfly is characterized by 2 obvious marks. The first one is a blue dot usually found in the middle of the wing encircled by a black stripe. The second one is at the bottom and composed of 3 colors: red, blue and black.