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ONE SPRING, while working on a book about foxes, I spent
several weeks camping alone in a tent at Trapper's Lake in Prince Albert
National Park, Saskatchewan. I had no running water or electricity, but I did
have visits from a mama moose with her twin calves, grey jays landing on my
Coleman stove, and bedtime music provided by wolves, owls, and loons.
Crawling from the tent one crisp morning to get the coffee
started, I was treated to an amazing sight. It looked as though someone had
decorated the shoreline trees and bushes with thousands of glittering golden baubles.
A closer look revealed that the sparkle came from sunlight shimmering on the
wings of legions of dragonflies that were clinging to branches.
Sometime before I arose, they had emerged from the water,
where they may have lived in their larval form for as long as five years.
Bursting from their old skins in a new shape, they had taken to the trees to
wait while their wings hardened and the sun warmed them. The empty white skins
they left behind littered the beach. In less than an hour, the dragonflies dispersed
to live the final months of their life, the dazzling spectacle of their
emergence unseen by anyone else.
I've always enjoyed watching dragonflies and their close
relatives, damselflies. Together, they comprise the insect order Ondonata,
which includes more than 5,000 species, living around the world in temperate
and tropical zones. Damselflies are generally daintier in body shape, and they
tend to rest with their wings folded up over their backs, or just slightly
open. Dragonflies are stockier, and rest with their two pairs of wings spread
flat. Harmless to people, dragonflies and damselflies are winged death to a
wide variety of insects, including mosquitoes, gnats and flies.
A dragonfly's huge, compound eyes provide a 360-degree field
of view in which to seek prey. Each eye contains nearly 30,000 lenslets, or
ommatidia, and each of those functions independently, producing its own piece
of the surrounding view. The dragonfly's view of the world is sharpest across a
wedge above the horizon in front of it. Directly to the rear, the image quality
becomes poor, but still allows the insect to detect motion.
Scientists recently discovered that dragonflies employ an
optical illusion called motion camouflage, in which the dragonfly moves in such
a way that it appears to its prey as a stationary object, even as it attacks.
Dragonflies are the world's fastest insects, capable of
reaching speeds between 30 and 60 kilometres per hour. They can stop on far
less than a dime, and perform incredible aerial acrobatics. They may cover more
than 130 kilometres in a day. All this on wings that appear as fragile as soap
bubbles.
In reality, those wings are tough yet flexible, capable of
adjusting in many ways to provide optimum power and control. Something I find
amazing, given my own lack of coordination, is the fact that a dragonfly can do
dissimilar things with different wings at the same time, constantly adjusting
"on the fly."
On these golden mornings and sultry summer afternoons, when
the flash of light on crystalline wings catches your eye, I hope you'll pause
in your labours long enough to admire the sparkling dance of the dragonfly.
- REBECCA L. GRAMBO
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