Brachydiplax chalybea is a species of dragonfly in the family Libellulidae. It is known by the common names yellow-patched lieutenant, rufous-backed marsh hawk, and blue dasher. It is native to much of eastern Asia, from India to Japan to Indonesia.
This species is found in many types of wet habitat, including brackish and disturbed waters. The males are seen more often, due to their territorial behavior. Females oviposit by "flicking" an egg mass out of the water into rocks and vegetation nearby.
