Parthenos sylvia[Cramer 1776]
Other name: Clipper butterfly
It can be found in South and South-East Asia, mostly in forested areas. The clipper is a fast-flying butterfly and has a habit of flying with its wings flapping stiffly between the horizontal position and a few degrees below the horizontal. It may glide between spurts of flapping.
Photos have been taken at Oasi Sant Alessio aviary