Green Darners

     Green darners are a common species of large dragonflies that live throughout most of North America, and Mexico, Central America and the Caribbean.  We here in the Middle Atlantic States see this kind of three-inch-long dragonfly with a three-inch wing span careening speedily over most every body of still water in the area from mid-April to early in autumn.  During summer, all dragonflies, including this type, catch and feed on a variety of flying insects, including mosquitoes, flies and moths.
     Dragonflies, including darners, are agile, opportunistic predators, well equipped for catching flying insects.  They have two large eyes that encompass most of their heads and give them excellent vision to spot prey.  They have four large, maneuverable wings to track down insects in flight, but are held straight out from the thorax, like a plane's wings, when at rest..  Wings on darners are clear.  And the six legs of all dragonflies, also extending from the thorax, are used to catch prey.
     The heads and thoraxes of male green darners are green, while their long abdomens are pale-blue. The heads and thoraxes of female and young darners are green, but they have green or brown abdomens.  The bodies of all darners are darning needle-like, hence their name.  And all darners have a black spot on the tops of their foreheads, in front of the eyes, which is bordered by thin, blue and yellow lines.  That black dot looks like the pupil of an eye, edged by lids that never close.  Its purpose probably is to intimidate birds and other would-be predators from eating green darners.
     Each male darner patrols a stretch of still water where he chases away other males and pursues females to mate with them.  Female darners spawn eggs in aquatic vegetation under shallow water.  Their mates use pincers at the end of their rears to clasp the females between their heads and thoraxes while they spawn.  The purpose is to keep other males from disturbing the egg laying.  The resulting nymphs are brown, which blends them into their surroundings on the bottom of impoundments.
     Dragonfly nymphs are aggressive carnivores, shooting out their lower jaws that have hooks to snare and eat aquatic insect larvae, tadpoles and small fish.  Most darner larvae overwinter as such and emerge from water the next spring as young adults ready to fly, catch insects and reproduce.           In September, many green darners migrate south to the southern United States, Mexico, Central America and the islands of the Caribbean to escape the northern winter.  Thousands of them may go south in great swarms, feeding on flying insects along the way and competing with migrating swifts and swallows doing the same thing.  It is felt by many scientists that those darners breed in their wintering grounds when they arrive, their larvae overwinter there, but come north during the next spring to spawn in northern waters.
     Watch for the interesting dragonflies, including green darners, this summer and fall.  They are all interesting and entertaining speeding over water and fields after insect prey and spawning in pairs in shallow water near the shoreline.