The Blue Dasher [Pachydiplax longipennis] is a dragonfly of the skimmer family. It is common and widely distributed in the United States.
Mature males develop a bluish-white pruinescence on the back of the abdomen and, in western individuals, on the thorax. They display this pruinescence to other males as a threat while defending territories at the edge of the water.
Although the species name longipennis means “long wings”, the wings are not particularly long. Females do, however, have a short abdomen that makes the wings look longer in comparison.
Photo: Atlanta Botanical Garden, Atlanta, Georgia, USA [20130913]
Source: Wikipedia