Monday, October 7, 2013

Dragonflies...Yes. Mosquitoes...No

Dragonfly resting on redroot flower

In the late afternoon, Ralph and I were sitting in the gazebo talking with a visitor when the topic of mosquitoes came up.  “Do you have many?” our guest asked.  With a lake within sight, I’m sure he imagined our response to be, “Yes.” 

Instead, we told him “No.  Thanks to dragonflies and bats, mosquitoes aren’t that bad here.”

Our response was reinforced that evening when Ralph and I took a pre-dark dip in the lake.  As we lolled in the sun-warmed water, a swarm of dragonflies filled the sky. 

“I don’t think I’ve ever seen this many dragonflies at once,” I exclaimed as a battalion of drone-sized fliers zoomed back and forth above our heads. 

The dragonflies were large – two to three inches long – and they flew with intention, showing no signs of hesitancy or indecision.  They didn’t land upon reeds as they do during daytime nor were they chasing each other in territorial battles or mating maneuvers.  Instead, they flew fast and furious, focused, it seemed, on a single mission: Catching bugs.  
I was awestruck watching them sweep across the lake, fortunate to be protected by troops of aerial warriors.

Red skimmer dragonfly on bog button
Between dragonflies and bats, which appear shortly after the dragonflies, the mosquitoes that live around our lake have much to fear.  Both consume quantities of bugs.  Although dragonflies and bats are both voracious carnivores, a dragonfly’s predatory skills are so well honed it manages to catch 95 percent of its prey.  In addition to mosquitoes, dragonflies also eat flies, gnats, bees, moths, butterflies and even the occasional spider in whose web they might find themselves entangled.

Bog buttons seem to be favorite landing pads for dragonflies of all colors and sizes

The wind wasn’t blowing as Ralph and I enjoyed our soak, and after the dragonflies appeared, it remained calm for about 15 minutes.  Then suddenly, a strong breeze blew in and our airborne navigators vanished.  We were still in the water a short time later (it felt too pleasant to get out) when the wind subsided and the dragonflies returned.  Around the same time, about half-dozen bats swooped in to do their sonar-directed search for supper above the lake and surrounding shoreline.

“Do you think we did anything to attract them,” Ralph asked as we dried off with towels on the way to the house.  We’d finally managed to extract ourselves from the lake’s warm water, leaving the dragonflies and bats behind to continue their feeding frenzy without a human audience.   

Although I didn’t have a definitive answer to his question, I presume dragonflies and bats live on our property because they find the habitat suitable.  There are plenty of dead trees for cavity-roosting bats to live in, shallow, marshy areas for dragonflies to frequent and no harmful pesticides or herbicides to disturb natural rhythms.  I also realize their presence could just as easily be the result of chance.

A few days later, we once again found ourselves lolling in the warm water in the twilight hours after a busy day of work.  As usual, dragonflies flew overhead albeit fewer this time than before.

Close-up of blue dasher dragonfly

“I love watching dragonflies,” I said from my semi-submerged perch.  “I may not know why they’re here, but I’m glad they are.”

As daylight diminished, we headed inside for dinner, happy to know that while we were dining on a vegetable stir-fry, a contingent of natural predators was zooming back and forth above the lake feasting on meals of their own.

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