Blue Dasher Dragonfly

A small blue dragonfly with a white face, a black tip to the abdomen, and a black-and-yellow-striped thorax. Females are recognized by the narrow yellow parallel stripes on the abdomen. Both sexes have an amber patch at the base of each hindwing. Males develop a sky-blue (or Carolina-blue) abdomen when they approach maturity.
California specimens turn blue not just over the abdomen (hiding the dark tip), but the thorax as well, and often have no amber on the wings at all.