STORY AND PHOTOS BY SUSAN TRUDEAU

Ferocious predators roam the streams and meadows of Illinois' wetlands and wild open spaces. These stealthy hunters lurk silently beneath the water's surface, waiting for their next meal to come along. Then, with lightning speed, they lash out their enormous lower lips, grabbing their unsuspecting victims. Later, they take to the air, attacking and eating their prey in mid-flight.

But don't let the presence of these fierce creatures keep you from visiting your favorite fishing spot or swimming hole this summer. You can enjoy watching their graceful flight and admiring their iridescent beauty while remaining perfectly safe—unless you happen to be a mosquito. These ferocious predators are the beautiful, and often misunderstood, dragonflies.

Halloween Pennant

Having taken wing from the earth's primordial swamps 300 million years ago, dragonflies are among our oldest living creatures. Although the dragonflies of today are considerably smaller than their 18-inch ancestors, in many ways, the insects remain unchanged.

Dragonflies look very much like their relatives the damselflies, however, there are obvious differences which make it easy to tell them apart. Both possess two sets of wings, but at rest, a dragonfly holds its wings straight out from its side, while most damselflies fold their wings back. Dragonflies have large eyes covering most of their heads, while a damselfly's eyes are set much farther apart. The dragonfly's abdomen is usually somewhat flattened while a damselfly's is more round and needle-like.

Southern folklore tells of dragonflies reviving snakes from the dead—hence the name "snake doctor." Dragonflies also are known as "devil's darning needles" because of their supposed ability to stitch together the lips of the wicked.While neither of these bizarre nicknames has any factual basis, the name "mosquito hawk" is well-deserved. During its life span, a dragonfly consumes thousands of insects, mostly mosquitoes. A park with a large dragonfly population is a much more pleasant place for people since they help keep in check the number of insects who look upon humans as their next meal.

According to Everett D. (Tim) Cashatt, PhD, curator of zoology at the Illinois State Museum, Illinois is home to at least 99 of North America's 307 species of dragonflies, including the endangered Hine's Emerald dragonfly (Somatochlora hineana). A rather drab and unremarkable-looking dragonfly were it not for its vivid green eyes, the Hine's Emerald was once located throughout Illinois, Indiana, Wisconsin and Ohio.

Today, human encroachment on the dragonfly's preferred habitat has threatened its very existence, and the Hine's Emerald is found only along the Des Plaines River, within the protective boundaries of the Forest Preserve District of DuPage County's Waterfall Glen Forest Preserve.

A major problem for the rare dragonfly is that, while some species are able to thrive wherever they can find reasonably clean water, the Hine's Emerald is much more particular, requiring shallow marshes laced with clear, slow-moving streamlets.

Keeping the water clean and inviting to dragonflies, including the Hine's Emerald, is crucial to their survival because dragonflies spend most of their lives underwater. The life cycle begins when the

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OutdoorIllinois

Male Widow Skimmer

female dragonfly lays her eggs in or near water; with some species preferring the still water of ponds and lakes and others preferring streams. Eggs hatch in five to 10 days, depending upon the species.

During this second stage of life, the dragonfly larva (also known as a nymph or naiad) is drab and unremarkable looking. But looks are deceptive. These tiny creatures are voracious hunters and eaters, gobbling up not only mosquito larvae but also, on occasion, minnows, tadpoles and smalt crustaceans. The outsized hunting skills of these tiny creatures usually mean the dragonfly larvae is at the top of the food chain in freshwater habitats without fish.

The dragonfly nymph may molt as many as 15 times and grow up to 20 times its original size before climbing out of the water and undergoing its final metamorphosis. The skin along the nymph's back dries out and splits open, and the adult dragonfly emerges.

Taking to the air, the dragonfly cruises streambeds and open meadows in search of mosquitoes. Grabbing its prey in mid-air, the adult dragonfly may eat as many as 300 mosquitoes a day.

Food is not the only thing the dragonfly hunts. Most species survive as adults only for a month or two, so mating is an urgent priority. Like eating, mating takes place during flight. The female then lays her eggs, and the circle of life continues.

Like birds, some species' of dragonnflies have remarkable color variations between male and female. For example, in one common Illinois species, the widow shimmer (Libellula luctuosa), the male has a powder-blue abdomen, while the female's is black with a bright yellow stripe. The female also lacks the white wing bands that so definitively identify the male.

"Sexual dimorphism in color is not well understood," admits Cashatt. "The differential color may enable males to better recognize each other when establishing breeding territories, and may help them distinguish females. Most female dragonflies spend more time near the cover of vegetation and less time near water. Their duller colors may give them better protection from predators."

Dragonflies are considered an indicator species on the health of a wetland environment, meaning that the presence or absence of dragonflies helps scientists determine the health of the environment. Human actions that affects the health of ponds, riverbeds and marshes can have devastating effects on dragonflies. Sewage contamination and fertilizer run-off from farms and urban lawns promote bacterial and algal growth, which depletes oxygen supplies in the water. Pesticides kill dragonfly larvae. Dredging streambeds destroys aquatic plants, robbing dragonflies of perches near the water. Damming streams and rivers turns flowing water into ponds, and rare stream dragonflies are replaced by common pond species.

Fortunately, Illinois still has open spaces and clean waterways capable of supporting healthy dragonfly populations, thanks in large part to our state parks and forest preserve districts.

While dragonfly watching has not yet developed the following bird watching has enjoyed, it can be just as rewarding a hobby. A pair of binoculars and a good field guide, such as Dragonflies through Binoculars, by Sidney W. Dunkle, are helpful for spotting and identifying dragonflies.

"The most diversity can be found in areas that have a variety of habitats," Cashatt says. "The Des Plaines Conservation Area and the Pine Hills Recreation Area with open fields, marshes, ponds, river and stream habitat should provide a variety of different species for the dragonfly watcher."

For more information on dragonflies, visit the Illinois State Museum's Research in Entomology page at www.museum.state.il.us/research/ entomology/index.html.

Susan Trudeau is a freelance writer from Champaign who frequently writes about nature and environmental issues.

August 2001

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