Connecting Lake Simcoe's Community

Protected wetland is a haven for bug-eating dragonflies

20140713 Ken Reid CA 1By David Hawke -- As we sat by the lakeshore, basking in the setting sun, we marveled at the air show being performed in front of us. The loop-the-loops were incredible, the mid-air formations almost heart-stopping, and the assertive manoeuvres to claim air space certainly demanded respect. A bonus to this event was that there were no screaming jet engines, no withering exhaust fumes or tell-tale contrails, just a ballet of motion.

          Dragonflies, with their four blade-shaped wings, are perfectly designed to patrol the jungle of vegetation which grows lush along the waterways. While in flight, they can hover, reverse, go straight up, drop down, or go to 'warp drive' in a blink. Although they are lean, mean, eating machines, they can be one of your best friends on a hot summer's day.

          These flying insects are predators, eaters of other living things, and they are always on the lookout for their next meal. Fortunately for us, deer flies and mosquitoes are high on their list of preferred morsels. When a target is sighted, the dragonfly holds its bristly legs together to form a net or basket and then, like a kid with a dip net, simply swoops the unsuspecting prey right out of the sky. Puts a whole new meaning on the term 'fast food'. A quick in-flight bite to subdue the captured insect and the dragonfly then settles down on a branch to enjoy a succulent snack.

          This is one flying insect that we humans do not have to be afraid of, as their mouthparts cannot possibly penetrate, or even pinch, our delicate skin. Even when you learn (as you are about to) that they belong to the order of insects called Odonata, and that 'odon' means toothed mandible, dragonflies are not a threat to us in any way, shape or form.

          Occasionally, one might land on you, and while their stiff, bristly legs and the bone-dry rattle of their wings may startle you, fear not. The reason they land on people is that people have a wonderful way of attracting deer flies and mosquitoes; the poor dragonfly doesn't know which one to chase first, so it rests a moment on your hat or jacket while taking a bead on a passing deer fly. In some cultures it is considered a sign of good luck when a dragonfly lands upon you.

          Should you have the opportunity to view a dragonfly up close, look at its wonderfully coloured compound eyes. Sometimes, if your eyes are good or you actually remembered to bring your glasses, you can see that the surface of the eye is actually made up of tiny hexagonal facets. If you forgot your glasses, but have a set of binoculars with you, look through the binos backwards, and when you move it in close (like a microscope), you'll quickly discover a world of beauty you perhaps never knew existed.

          When it comes to compound eyes, the more facets there are, the better vision that insect has. Ants have six facets, while butterflies have over 2,000… but dragonflies have 20,000 or more! Deer flies that think they can cross through a dragonfly's territory undetected have but a short time to live.

          Even as a baby, or nymph, the dragonflies have been helping us out. After the eggs are laid on a plant stem near the water surface, the newly hatched nymphs crawl into the dark, cool cover of the lake or pond bottom. There they stay for one to three years (depending on the species) until they mature and emerge from the water to turn into a flying adult.

          While in the aquatic nymph stage, the little dragonflies are the terror of the wetland. They hunt down and capture all their food, and I'm delighted to report that mosquito larvae are at the top of their 'catch of the day' list.

          But let us now return to that shoreline where we first noticed the aerial manoeuvres of these frisky insects. Whenever a male enters into another's territory, the chase is on! The defending male will rush up to meet him, and a face-off begins. Head-to-head they will rise into the sky, sometimes hitting their wings together in a brittle crackling sound. Eventually, one backs down and flies away. The victor then returns to his favourite perch, once more Lord of the Shoreline.

          Despite their fearful sounding name, dragonflies are a great ally to us, as they eat lots and lots and lots of other insects that may like drawing blood from us. A protected wetland is a haven for dragonflies… let's do our part to ensure they always have a home to hover over.

David’s notebook: For those who like this hot and humid weather, your January wishes are coming true! As for me, I'm parked in front of the fan contemplating a bathtub full of cool water!

© 2019 David J. Hawke

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Sunday, 17 November 2019

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