Our Window on Nature

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A Tale of Dragons and Damsels

Filed under: Bugs — Lowell Christie -- June 25, 2016 @ 10:03 am

DragonflyThese dragons don’t chase damsels in distress. As a matter of fact, they don’t chase much of anything except small flying insects acceptable as food.  Oh yes, and other dragonflies.

At a length of two to five inches, dragonflies are the modern world’s largest insects, but they’re puny by ancient standards. A dragonfly imprint dated to the time of dinosaurs boasts a wing span of 30 inches. That’s appropriate when you consider the size of the dinosaurs that frequented the same rivers and ponds, but imagine one flying into your hair.

Of course, we weren’t there to see the early dragonflies or the dinosaurs. Anyway, large size wasn’t such an advantage. as those big fellows achieved extinction while the smaller versions are still around.

Today’s dragonflies (Odonata) are the world’s largest and some say the world’s fastest insects. Found worldwide, they number over 6,000 species – that’s half again as many species as mammals. Scientists divide them into three groups: Dragonflies, Damselflies, and a very small third group, called Ancient Dragonflies.

Odonatology, the study of Damselflies and Dragonflies, is becoming quite popular among amateur naturalists. (To get technical about it, students of dragonflies and damselflies are odonatologists, or if that’s more than your tongue wants to handle, among themselves they admit to being odomaniacs). Some of these may have contributed a few of the colorful names attached to the dragons and damsels of North America, like Jewelwing, Rubyspot, Threadtail, the Darner and the Dancer, Sprite, Firetail, and the Fragile and the Furtive Forktails. The imagination goes wild just thinking of such creatures.

How do you know whether you’re looking for a dragon or damsel? For the most part, dragonflies are larger than damselflies, but there’s an easier way than getting out a ruler. When at rest, dragons spread their gossamer wings at right angles to their bodies. The wings of resting damsels, on the other hand, are swept back but held above their bodies. Neither of their primitive groups possess the ability to simply rest their wings on their backs as do more modern flyers.

The designation tigers of the insect world results from the creatures’ hearty appetites. Some species hunt from a perch, resting on a twig or rock until a delectable morsel sails by and then snatching it from the air. Others hunt during flight. Their legs are long and slender, armed with a row of stiff bristles along each side. When flying, the insects hold their legs slanting forward to form a basket or scoop to snatch flying prey. They dine mainly on flies and other small critters (including, one hopes, a huge quantity of mosquitoes). They can deliver a nasty bite to human hands, but only do so to unwary naturalists who have netted them for study.

Like other insects, dragonflies have compound eyes, but theirs are immense. A bulging arrangement of ten to thirty thousand facets point up, down, forward, and backward. You don’t sneak up on a dragon or damsel without it noticing.

Typically, the adults emerge in the summer, and live only long enough to feed and to lay eggs on or in the water. Soon the eggs hatch into nymphs that feed and overwinter underwater. This scenario isn’t true of all species, however. Some nymphs require more than one year to mature. The adults of some species live longer than a month or so and they migrate with the seasons.

Entomologist Michael May, of the Dept. Of Entomology, Rutgers University, researched the spring and fall migration movements of several species of dragonflies and posted a request over the Internet that other enthusiasts send their own sightings from Maryland. He indicated that large cloudlike swarms of dragonflies are common along the coast in the fall. In spring, he says, the northward movement of these species tends to be more inland. They’re more likely to move individually than as a swarm.

The idea of seeing a swarm of dragonflies sounds exciting, but also eerie. Butterflies yes, but swarms of dragonflies seems more like an invasion.


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