is actually a butterfly./.....Blue spotted crow butterfly, Euploea midamus.
They have stunning blue wings, although they tend to keep them closed when they are feeding.
You may have seen swarms of these sometimes on their favourite plants, maybe 30 or so on one bush, and as you get close they take off and flutter gently around you, a wonderful experience.
Here a close up showing the delicate veins in the wings, and the white spot patterning on the body.