White Dragontail: Feeding on false heather . . .
White Dragontail is a medium sized butterfly , wing span ranges from 40 to 45 mm. Wings are mainly black, the triangular forewing with hyaline cells, short and narrow radial cells in the hindwing, and has a pair of slender tails which looks like swallow's tail. Its adult is the smallest in the Papilionidae family in the world.
Ref: Fung Yuen Biodiversity Series. White Dragontail by Pun Sui Fai.
When feeding, they stay on one flower very briefly, usually for a second or two, then swiftly jump to another with no predictable route Capturing them in motion is a great challenge.