365 Urban Species. #204: Blue Dasher
Jul. 23rd, 2006 06:11 pm
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Urban species # 204: Blue dasher Pachydiplax longipennis
Dragonflies exist with a very curious mixed public image. Happily, the great majority of enlightened people recognize them as important predators, waging an aerial assault on the mosquito hordes that plague us. A significant minority of people are still alarmed by their appearance, mistaking them for stinging wasps or worse. Dragonflies are unable, as well as disinclined, to attack humans. They do not suck blood but instead catch whole prey in midair. Their young are even more misunderstood. Covered with muck, wingless and drab, a dragonfly nymph is a frightening ogre. Yet in its element, it's as important as its adult form, if not more so. Dragonfly larvae are the prey of sunfish, frogs, turtles. and herons. In this way they form an important link between the smallest and largest animals in an urban pond environment.
The blue dasher is a common, medium-sized dragonfly, found throughout most of populated North America. Any still water, from a canal, to a pond, to any number of industrial sites, can harbor enough prey to sustain some amount of dragonflies. Their pale blue body color and huge, shining green eyes make the blue dashers an exciting species to encounter. Hobbyists, similar to (and often drawn from the ranks of) birders, perch on the banks of marsh water, binoculars in hand, watching the territorial behaviors of these attractive insects. Conservation organizations have begun including "odonates" (dragonflies and damselflies) as a top taxonomic group in their biodiversity surveys.