Blue dasher

Pachydiplax longipennis

The blue dasher is a dragonfly of the skimmer family. It is common and widely distributed in the United States and Canada.

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 substantially longer than those of related species. Females do, however, have a short abdomen that makes the wings appear longer in comparison. The blue dasher grows up to 25–43 mm long. Juvenile males will show female coloration before they turn blue. Females are paired with yellow stripes on the dorsal side of the first 8 abdominal segments, the part of the body that lies between the thorax and the pelvis and encloses the stomach, intestines, liver, spleen, and pancreas; more commonly known as the belly. Females are also reported to turn blue, but at a slower rate then the males.