Caliaeschna microstigma

A small dragonfly with a body length of 50-60 mm and a hindwing length of 35-41 mm, the dark, short pterostigma and, in males, the light blue, boomerang-shaped antehumeral stripe in the thorax, are diagnostic. The eastern lives in fast-flowing water in hilly and mountainous regions, in partly-shaded streams and small rivers with hydrophytes and trees whose roots are directly above the water. This species flies June through August, flight zigzagging low over the water.

 

Attribution: Nikolai Yunakov (Wikipedia Creative Commons)