Dragonflies and Damselflies: Nature’s Acrobats
Photo: Carol Shirk
Living as we do in an area of abundant waterways; it is hard to meet a person who has not encountered dragonflies and damselflies. Dragonflies are the more widely recognized of the two, but damselflies play an equally important role in the ecosystem.
Dragonflies have several nicknames, some accurate, some not. One obviously false nickname—“the devil’s darning needle”— arose because it was thought that some of the large species would sew shut the eyes and ears of sleeping children. Another, “the horse stinger,” is equally false. These insects cannot sting and are peaceful and enjoyable unless you are a flying insect like a mosquito. A third nickname, “mosquito hawk,” is most accurate, as these insects eat copious numbers of mosquitos in their lifetime.
Both dragonflies and damselflies are in the order Odanta. When at rest, dragonflies have their wings extended like an airplane, while damselflies have theirs folded at their backs. They spend most of their lives in the water. Their simple, three stage life cycle is composed of egg, nymph (called naiads), and adult. Only the adult form lives on the land.
Eggs are laid on or near the water with each female laying hundreds of them. The nymphs live essentially buried in the mud from several months or up to three years feeding on other insects, mosquito larva, tadpoles, worms, or even small fish. These wingless creatures do not resemble their adult counterparts and are quite difficult to recognize.
When they are fully grown, and after several molts, they crawl out of the water for the final, 30 minute long, molt into a magnificent adult. They can take flight within an hour or so after their wings dry, although this is a vulnerable time for them.
Dragonflies and damselflies are voracious and aggressive predators. Their huge eyes take up most of their heads and the design of their bodies allows them to spin, twirl, dive, and fly with great agility. They can hover, fly sideways, upside down, backwards, and spin 360 degrees. They consume primarily flying insects, including flies, midges, beetles, and mosquitoes. Because mosquitoes make up a portion of both the larva stage and the adult stage, they are part of nature’s pest patrol. Although the adult life span for dragonflies is only about six weeks and damselflies is 3-4 weeks, they consume a significant number of pest insects in that time.
The Navajo culture of the Southwest United States believes dragonflies to be a symbol of water purity. This belief is scientifically accurate, as many species require good water quality to survive. In addition, the National Park Service along with citizen scientists have conducted a mercury analysis study since 2011 using dragonfly larvae. The Dragonfly Mercury Project collects dragonfly larvae to determine mercury levels. The food source for these larvae can contain mercury and it builds in the larva cells. Mercury is a toxic pollutant to both humans and animals and can come from sources, including air pollution at great distances. In this way, the Park Service can determine the health of the National Park Service waters.
Dragonflies may have only a wee rice-sized brain, but they make up for it in their beauty and benefit to the human race. They make our world a more beautiful as well as a healthier place to live.
Carol Shirk
Certified Master Gardener