Dragons and Damsels in our Midst

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Common Green Darner
When summer heat and monsoon rains come to Arivaca, it’s prime time for our local population of dragons and damsels… as in dragonflies and damselflies!  These two members of the Odonata family of insects are some of the most interesting and amazing creatures that live on the planet, and some of the most beautiful too.   

 When ponds and other riparian areas fill up, it benefits the “population explosion” of all our local Odonata, which in turn benefits all Arivaca-area residents by greatly helping to control local mosquitoes in our won backyards. Dragonflies and damselflies have been around for a very long time.  In fact, 200 million year old fossils of ancient dragonflies have been found that had 27-inch wingspans!  I wonder what those “flying tigers” ate for breakfast?   

Eight-spotted Skimmer

Today, the largest Odonata have wingspans of 5-6 inches, yet their tremendous hunting ability is incredible:  
  •  They are the fastest-flying insects in the world and have been clocked zooming well over 30 miles an hour, so that pesky mosquito hovering around your head doesn’t stand a chance against them!  

  • Their eyes move independently in every direction and can see from a far distance, so not only can they see prey from great heights, they can even see prey that is behind them;
  • When they swoop in fast and furious for a kill, they can experience a G-force of 4, similar to what fighter pilots experience, and it can increase to 9 when they make a sharp turn.  However, unlike fighter pilots who wear compression suits to force the blood out of their legs and into their brain to prevent loss of consciousness, Odonata do this automatically in a split second, with no suit needed.   

  • Their four wings can move independently from one another also, giving them the ability to turn on a dime, fly slowly or hover, glide, and just plain out-maneuver any other flying insect;
  • Their nymphs (larvae) crawl around the bottom of local ponds and lakes, and voraciously hunt all night and day.  In fact, because many Odonata species live longer as nymphs than as adults, they prevent millions of mosquito larvae from even having the chance to become adults. Some nymphs can even prey on small fish! 

Western Pondhawk
You may also be surprised to learn that after mating, most female Odonata lay their eggs on water grasses and other plants, sometimes diving down deep in the pond.  They are able to breathe via a protective coating of air that gets trapped in the many fine hairs on their bodies.   Their eggs hatch into nymphs, and go through a series of molts as they grow and develop, much like other land insects.  At the end of the final nymph stage, they climb out of the water onto a stone or a plant stalk, or even some algae floating at the surface.   



Exuviae (exoskeleton) from damselfly and dragonfly

Then the nymph splits its last larval skin open along a suture on the back of the thorax, and pulls itself out through this hole, kind of like how we humans take off a sweatshirt.  And when they fly away, all that's left behind is their empty exoskeleton, called the exuviae.

 Some species have a short nymph stage (1-2 months from egg hatching to emergence from water), but most spend at least a year as aquatic larvae, and some spend 5 years or more as nymphs!



I am very lucky to have learned a lot about Odonata from one of the foremost experts in the world, Dennis Paulson.  If you’d like to learn from him too, my radio show interview with him is available to listen to anytime at the Magnuson Children's Garden website! In researching for this article, I also discovered a fantastic website with online field guides to the plants and animals of the Sororan Desert.  It lists 20 Odonata species that can be found in the Sonoran Desert, with great color photos and descriptions, and links to other sites.   Next time you’re out in the back yard, or on a Cienega walk, visit www.arizonensis.org/sonoran/fieldguide/arthropoda/odonata.html and see how many you can identify.  Happy exploring!

Photo credits:
Common Green Darner by Dennis Paulson
Eight-spotted Skimmer by Dennis Paulson
Western Pondhawk by Dennis Paulson
Exuviae by Dennis Paulson

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