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Dragonfly Fascination
by Douglas A. Spilker, Ph.D. - posted 02/27/18

The striking azure color of the very common blue dasher only develops as the dragonfly matures.


Dragonflies with their ominous beauty, vivid colors and their spectacular flying maneuvers have provided hours of entertainment for many gardeners. Dragonflies are widespread across the United States and can be enticed to visit most yards. There are more than 450 species found throughout the United States and Canada. They range in color and size from the small eastern amberwing to the very large and brilliantly colored green darner. Although these insects tend to stay close to their birthplace, they are strong fliers that will explore surrounding areas. So if you garden even remotely near fresh water or a wetland, you can lure dragonflies to your yard.
 

 

The giant darner is thought to be the largest dragonfly found in the United States, with a wing span of up to 5 inches. Here it is shown during mating.
 

The eastern amberwing is one of the smaller dragonflies and looks very “wasp-like” in flight.

Their Water World
There is a good reason that you see dragonflies and damselflies around ponds, lakes and streams: They are aquatic insects that spend the majority of their lives developing in these wetland habitats. A dragonfly can have a life span of more than a year, but spends very little of that time as an adult dragonfly. There are three stages of the dragonfly life cycle: the egg, the nymph and the adult dragonfly. Most of the life cycle of a dragonfly is carried out in the nymph stage, which you will not likely notice unless you are attentive when cleaning out the bottom of your pond. Once the dragonfly eggs hatch, the larvae begin as wingless nymphs that look like little alien creatures. These six-legged nymphs live in the water feeding on other aquatic insects and small fish, while they grow and develop into dragonflies.

Dragonfly nymphs live in ponds or marshy areas because the waters are calmer than in a stream or river. When dragonflies are present, it is an indication that the ecosystem is in good shape since they are very sensitive to pollution. Once the nymph is fully grown, and the weather is right, it will complete its metamorphosis into an adult dragonfly by crawling out of the water, up the stem of a plant to shed its skin. Though dragonflies are predators, they themselves are subject to being preyed upon by birds, frogs, spiders, fish, water bugs and even other dragonflies, especially during this vulnerable stage of emergence. Once they become mature adults, their exceptional vision and nimble flight abilities make them a difficult catch.


An eastern pondhawk perched devouring its recent prey.


Voracious Hunters

Dragonflies tend to perch on upright sticks, plant stems and even plant stakes, basking in the sun’s warming rays. This widow skimmer appears to have just avoided being another’s meal!

Dragonflies are predators of anything they can hunt down, especially small insects like mosquitoes, midges, flies, mayflies and even honeybees. They may look menacing but pose no threat to humans. Dragonflies are known as the aerial acrobats of the insect world. Adult dragonflies have two pairs of transparent wings, with each wing having the ability to beat independently, making them capable of flight in all directions. Therefore, dragonflies are highly maneuverable hunters and very adept at intercepting prey in midair. By forming a basket with its legs, a dragonfly can scoop up both flying and perched insects without stopping. No toxins are used, and their prey is usually eaten alive. Some of the larger species, like darners, will just open their mouths and swallow small insects in flight.

Although the nymph stage may last from months to years, the adult stage only lasts about six weeks during midsummer. This is the last stage of a dragonfly’s life, and the stage for reproduction. Females can be seen laying eggs by tapping the tip of their abdomens directly into the mud or on emergent plants in the shallow water at edges of streams or ponds. In addition to searching for prey, males patrol their territories seeking females and driving away rival males. Mating pairs can often be seen flying or perched in tandem.


Eastern amberwing on a water lily flower.


You Ought to Be in Pictures
Dragonflies need water, so installing a pond or pool is an assured way to attract them. Even a small water feature like a half whiskey barrel can be enticing. Dragonflies seem to be more active when they have an opportunity to warm themselves, so place your water feature where it will receive midday sun. Although it is enjoyable to watch dragonflies dart about on a summer’s day, it is even more fascinating to see them up close, maybe capturing a photo of their brilliant colors and intricate wing venation. Dragonflies tend to perch on upright sticks, plant stems and even plant stakes, basking in the sun’s warming rays, or devouring their recent prey. It is best to forego the urge to trim the vegetation right down to the pond’s edge, but rather be sure to leave a fringe of tall grass or weeds as resting places. The dragonflies will likely repay your kindness with some astonishing poses!

 

A version of this article appeared in a January/February 2015 print edition of State-by-State Gardening.
Photography courtesy of Douglas A. Spilker, Ph.D.

 


Douglas A. Spilker, Ph.D., is a consulting ornamental plant pathologist and entomologist, garden writer and lecturer. Dr. Doug can be reached at askdrdoug@gmail.com.