Like other dragonflies, blue dashers (Odonata: Libellulidae: Pachydiplax longipennis) are typically found near water. They can be encountered anywhere from southern Canada to northern Mexico, usually near lakes, ponds, marshes, and bogs. Their aquatic nymphs are notable among dragonflies for having a high tolerance for poor water quality and low oxygen.
A blue dasher can be identified in part thanks to a distinct set of yellow stripes on a dark thorax. In addition they usually feature amber spots near the bases of their hind wings and have abdomens that are tipped in black. Coloration, however, varies significantly between the sexes. Females and young males are almost completely yellow and black and have reddish eyes like the individual above. Females retain this coloration but the abdomens and eyes of males gradually turn bluish with age.
Males eventually turn almost completely blue, although they do retain their yellow thoracic stripes.