Monday, January 25, 2016

Odonata always serves up humble pie

Imagine someone holding up a creature before me. It has fins and gills and there are scales covering its entire body.
"What's this?" he asks.

If I were to reply, "It's a fish," he would think I was just being a smart aleck. But I don't say that. Instead I reply, "It's a tulibee," or a redhorse sucker, or rockbass, whatever the specific species happened to be. That's because I know my local fish species.
Yet, if he held up the creature in the photos above, in most instances I would have to say, "It's a dragonfly." I'm ashamed to say that's about as specific as I could get without comparing it to my dragonfly book first and maybe even afterwards.
Part of the problem just comes from the numbers in the Order Odonata. There could be upwards to 100 species of dragonflies and 40 species of damselflies in Northwestern Ontario alone. By comparison, there are only about 20 species of fish and probably about the same number of minnows.
I really need to study dragonflies more because I think they are just the most amazing things. For starters, they are absolutely beautiful with their intricate wing patterns and neon colours. And their style of flight must be the envy of every airborne creature. They hover, make right-angle turns, and reach amazing speeds for such small bodies.
Some dragonflies hover as they hunt; some fly back and forth to a perch. Some stay strictly around the water; others will go miles inland. Some are territorial; others are communal.
But they all eat other flying insects, including the ones that like to feed on us humans.
I love the feeling of symbiosis I get when I'm mowing the grass in the summer and behind me are dozens of dragonflies, like helicopters in a scene out of Apocalypse Now, killing every mosquito and blackfly that take wing after being disturbed by the mower.
These miniature choppers are just the adult stage of the insect. They spend years underwater as swimming and crawling -- but still predatory -- bugs that look more like crickets than dragonflies. Each species emerges at a different time during the summer, goes through a type of metamorphosis something like a butterfly, and takes to the air. These adults mate and lay their eggs back in the water to start again. Some live as adults only a few weeks but others make it through the entire summer. There are even a couple of species that migrate to the U.S. south. There they deposit their eggs in the water and, when they emerge as adults, fly all the way back up here.
Although they are considered to be cold-blooded in that they lack the system to create body heat, they do in fact, get warm, up to 110 F, just by burning calories in flying. If you see a dragonfly that periodically plops into the water, it is trying to cool off.
The very name -- dragonfly -- conveys a mythical and romantic vision. They have been around for a long time, at least 300 million years. Back then they were a foot and a half long or about the size of a large duck!
So, getting back to the photos up top. What species is this? If you know, please leave a comment.
My best guess, after consulting my favourite field guide, Dragonflies of the North Woods by Kurt Mead, published by Kollath-Stensaas Publishing of Duluth, Minn., is that it is a Shadow Darner.
I'm led to that conclusion by the shape and yellow colour of the marks on its thorax as well as the blue spots on its abdomen. It's scientific name is Aeshna umbrosa.
My book says it likes to follow along streams and wooded edges and sometimes hunts in swarms. I found this one in the yard at camp last summer. It could have been part of the squadron following the mower.

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Unknown said...

Because of their mosquito eating ability we refer to them as the A-10 of the insect world.
Bob Moninger

Joe Overman said...

Once again, you remind us of the wonders of Nature! Thanks!

Lonnie and Mike said...

LOVE dragonflies!!! Every year we get a hatching of them. They love the pond.