WILDER SIDE OF OAKLAND COUNTY
They ruled the skies before the time of the great dinosaurs and have survived cataclysmic extinction events that eliminated other species. Masters of incredibly nimble flight who, in the blink of any eye, can change direction, speed, and elevation with aerodynamic skills that even the most modern high-tech helicopters cannot master. These voracious predators with huge eyes can accelerate to over 30 miles per hour. They are your best friends and guardians as you hike the wetland trails of Oakland County, or just relax on a warm summer evening. Of medical importance, dragonflies and damselflies capture and eat mosquitoes that may carry the West Nile Virus and the Zika virus.
The sultry days of late August belong to the dragonflies and damselflies of our county. I cringe when I hike with others and they flee from, or swat at, one of these hovering beauties for fear they will bite or sting. They do neither. They hunt mosquitoes and other small bugs as they hover near us. The heavy rains of last week assure another imminent mosquito emergence, but the dragonflies will be ready and waiting.
It took ultra-high speed filming technology to determine how mosquitoes are caught, but with the backing of the National Science Foundation the method was confirmed. Dragonflies use their feet to make the capture and then gulp the hapless victim down. Entomologist estimate they have a 90% capture rate during their hunting forays, an astounding number that far exceeds the ability of most predators. In the shallows of wetlands dragonfly larva hunt mosquito larvae and catch them with a highly specialized mouthpart that can spring forward just enough to snag and swallow prey with a slightly barbed lower lip.
Although dragonflies and damselflies are both classified under the order Odonata (meaning “toothed ones” a reference to their serrated jaws) and share habits and habitats, they are not the same insect. They are very easy to tell apart. The dragonflies, which are usually two or three times larger than a damselfly, hold their four wings stretched out when perched on a twig, while the more dainty damselfly folds their wings behind them and hold them up vertically.
Much of their life cycle is hidden from view, but every once in a while, the emergence from larvae to adult is witnessed. When the time is right, the larvae slowly crawls up from the wetland bottom onto emergent vegetation and clings on tightly. Over the next few hours it wiggles its way out of its exoskeleton, much in the way done by a cicada, and then slowly spreads its wings to dry in the sun, leaving the exoskeleton behind. Then it’s time to fly and look for mate.
The mating act is far more romantic to witness, than to describe. The male dragonfly or damselfly securely grasps the female behind her head with his “terminal claspers” at the “tail end” of his body, while the female curls her abdomen forward to join the male. The result is the formation of beautiful living heart that sometimes glimmers in sunlight as witnessed with these delicate Ebony Jewelwing Damselflies.
The photographic capture of the Halloween Pennant Dragonflies mating was an unexpected treat on the Wilder Side of Oakland County. I was with a wildlife biologist from the Michigan Department of Natural Resources at Kensington Metropark during an Osprey banding project. The dragonflies mated on a stick at the very edge of the occupied osprey nest, which brings to mind the timeless words of John Muir, “In every walk with nature one receives far more than he seeks.”
Jonathan Schechter is the Nature Education Writer for Oakland County Government and blogs weekly about nature’s way, trails, and wildlife on the Wilder Side of Oakland County.
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[…] American Ruby Spot Damselflies (Hetaerina americana) can be hard to spot, and next to impossible to photograph when in flight, but when it’s time for mating in the waning days of summer, and they assume their heart shape pose, they are stunning. I will confess, I have watched damselflies mate before, but never while sitting at a picnic table eating pizza. With that wild side encounter behind me I set out to explore the rest of the 10.3-acre park as I listened to water flowing over gentle rapids and watched songbirds in the shrubbery. As I stood to wander, I noted a Cooper’s hawk perched on a limb on the far bank and suspect it too watched the song birds – in hopes of a meal. […]