The Swallowtail butterflies are famous for their wing tails but very few can rival the tail length of this White Dragontail.
Evidently, the White Dragontail does not have the typical characteristics of a swallowtail butterfly (i.e large and colourful). In fact, it is the smallest swallowtail in the world with a wingspan of around 4cm.
The colours of the White Dragontail may be dull, but its flight pattern is exceptional----agile and erratic like a dragonfly. It is rare in Hong Kong and can only be found in a small number of locations.
Another distinctive feature of this butterfly is that the middle part of its forewings is transparent. This is unique in the swallowtail family.
In contrast, the Common Birdwing is not only among the largest (wingspan upto 16cm) but also the brightest coloured butterflies of the world.
Unlike the White Dragontail, the Common Birdwing does not have wing tails at all but has angular wings similar to the shape of bird wings.
Unfortunately, their size and beautiful colours make the Birdwings very popular with butterfly collectors. In Hong Kong, they are the only butterflies listed as a conservation concern. The butterflies and the food plant of their larvae (Indian Birthwort) are protected by law.
Regarding the rarity of butterflies, I think not many can beat this Common Mormon.
Looking carefully, you will find that this butterfly seems to be born with just one wing tail while the other one somehow didn’t develop.
I have seen tailless polymorphisms before but this butterfly is extraordinary.
More photos at Google+