Blue Dasher (藍額疏脈蜻)

The Blue Dasher (Pachydiplax longipennis) is a dragonfly of the skimmer family.
A Dragonfly in Blue (藍色蜻蜓)
Location: Kam Shan Country Park (金山郊野公園)

A Male Blue Dasher (藍額疏脈蜻)
Location: Tsim Shan (尖山)

The mature males of Blue Dasher do develop a bluish-white pruinescence on the back of the abdomen.

data source: wikipedia