photos:Jon Gardiner

s the morning sun spreads summer warmth onto meadows and ponds, the fearsome hunters prepare for launch, whirring their membranous wings to warm flight muscles for the day's hunt. Muscles taut, they vault into the air. They are gossamer death, skimming the landscape, their bulbous eyes enabling a panoramic view as they search for the slightest glint of prey. A river cruiser acrobatically flips its streamlined body, swooping to snag a mosquito in mid-flight for an aerial meal. A powdered dancer deftly dives to bring an untimely end to a plump housefly more than half its size. They fly constantly--the swamp darners, mocha emeralds, pondhawks, clubtails, jewelwings.

To Duke graduate student Joshua S. Rose, who studies their ecology, these elegant predators are as poetic in form and function as their species names. They fully deserve to be called by their mythical-sounding moniker: dragonflies. Rose enjoys describing the talents of his chosen study subjects. "They're incredibly agile, which is particularly amazing because fossil dragonflies from the Jurassic period of dinosaurs don't look much different from dragonflies today," he says. "And yet, you'd think that the true flies that are their prey, and which evolved much more recently, might be more maneuverable. But the dragonflies are just a heck of a lot faster and more powerful."

Modern dragonflies, fortunately, are much smaller than their ancestors, says Rose. Fossil dragonflies dating to the Permian period some 250 million years ago boasted wingspans of two-and-a-half feet. If those ancient adults were formidable, the dragonfly larvae, called "nymphs," were downright horrific, he says. Stalking the floors of ancient forests, the voracious nymphs measured more than a foot of downright nastiness. Beneath their heads nestled a hinged, armlike structure called a "labium" that ended in fanglike pincers.

Fans of the Alien movies, whose hellish monsters sport similar extensible dentition, will appreciate the deadly function of such a dining appliance. Like the movie aliens, a nymph encountering prey slashed out with its labium, snatching the hapless animal back to shred it in powerful mandibles. "If these ancient forms were still around today flying in the air, and their nymphs stalking the land, many biologists believe humans would still be living in caves," says Rose.

Fortunately, today's dragonflies are definitely benign, at least to larger animals. Belying their nicknames of "devil's darning needles" or "horse stingers," they do not bite. And, although the nymphs have retained their rather alarming eating habits, almost all species are now aquatic, spending their infancy in ponds and streams terrorizing worms, tadpoles, and small fish. The modern nymphs have retained their ancestors' decidedly uncouth breathing method of drawing water into their anuses to oxygenate gills inside their rectums. What's more, to escape danger, they can jet-propel themselves by forcefully expelling that water--bringing to mind a rather crude phrase occasionally used by humans as an insult. Fortunately, when adults emerge from their larval exoskeleton, they develop a more aesthetic breathing mechanism, drawing air through trachea along their body segments.