News about the health and beauty of the natural world that sustains us.
Pity my neighbor. He’s a foot-soldier in the war against weeds, a Saturday-morning guardian of bluegrass and a Monday-night warrior armed with Weed-be-Gone. He patrols his yard, head bent, weed-digger in hand, ready to pounce on any intruders. "Look!" he shouts, holding up the uprooted foe. There’s accusation in his voice. He blames me for his troubles because I happen to enjoy dandelions and do nothing to discourage them. They’re scattered across my lawn like constellations in a night sky. My kids like to pick them between their toes and rub yellow on their cheeks and say it’s butter.
I wander over to watch him engage the enemy, and notice, drifting with the breeze, the delicate parachute of a dandelion seed. My neighbor stands abruptly, roots dangling from his hands, and unwittingly intercepts the drifting seed. It lands on his head, perky as a daisy, then catches a breath of air and floats past his shoulder and settles among the grass on that rich and pampered soil. It will have no trouble competing down there.
The wind is a tremendous distributor of life, and plants and animals have evolved many mechanisms for taking advantage of it. Dandelion seeds, with their umbrellas of down, can ride a breeze for hours. The tiny plumed seeds of bulrushes and cattails have traveled hundreds of miles over open ocean and colonized remote islands. In summer above the temperate regions just about any cubic mile of sky contains millions of assorted seeds, insects, spiders, and other organisms. Suspended or drifting in the air much the way plankton drifts through the ocean, they fill the sky to an amazing height and can travel vast distances on the wind.
Life Will Find a Way
On the ice fields of Mount Everest, at a height of twenty-two thousand feet, lives a species of jumping spider that is probably the highest permanent inhabitant of the earth. Biologists early in the 20th century were baffled by the spider, because the harsh environment where it lived seemed to offer nothing for it to prey upon. But the spider only needed to wait for its meals to be delivered. Every day, countless flies, aphids, butterflies, moths, beetles, ants, gnats, midges, and mites were swept by updrafts to the top of the mountain and deposited on the ice and snow.
In the 1930s, a pair of entomologists in England launched a box kite equipped with a specimen net to a height of two thousand feet to see what they could capture. When they brought the kite down they were surprised to find it contained plant lice, flies, aphids, thrips, and parasitic wasps —a total of 839 insects. About that same time, an entomologist in the United States named Perry Glick logged more than fourteen hundred flights in a biplane equipped with screens between the wings. In the sky over Louisiana, at altitudes as low as twenty feet and as high as nearly three miles he collected more than thirty thousand individual insects representing seven hundred species. He concluded that a single square mile of air contains an average of twenty-five million insects, plus uncountable numbers of seeds, spores, pollens, bacteria, and other minute living things. In 1963 biologist L.W. Swan named this airborne bestiary the "aeolian zone," in reference to Aeolus, the Greek god of the wind.
Although most of the animals carried aloft by winds are probably unwilling travelers, many species of spiders use air transportation to disperse their young. On a sunny, windy day a spiderling ready to make its way in the world climbs to the tip of a twig or grass blade, raises its abdomen, and spins a thread of fine silk. When this silken lifeline waves six to ten feet into the air and is caught by the wind, the spiderling releases its hold and is carried away, ballooning into the sky. The journey it takes can be long and lofty. Spiders on gossamer threads have been captured more than five miles above the ground. Others have descended into the rigging of ships hundreds of miles from the nearest land.
The caterpillar of the gypsy moth is another enterprising aeronaut that makes good use of the wind. This voracious devourer of oak, aspen, apple, beech, and birch leaves is a true gypsy, sending out a silk strand that catches the air and carries it away. The hairs on the caterpillar's body are hollow, increasing its buoyancy and allowing it to be taken as high as two thousand feet above the ground, and across miles of countryside.
Lying on my back, in the yard, in a circle of dandelion blossoms, I can look up any summer afternoon and see insects drifting past on the wind. I don’t know how far they rise, but I can see the darting flight of insect-eating swallows so high they appear hardly larger than insects themselves. Life swirls and eddies to the very limits of habitation. If the wind blew across the vast and airless space between the planets, surely it would populate the universe.
Adapted from the national bestseller It’s Raining Frogs and Fishes: Four Seasons of Natural Phenomena and Oddities of the Sky by Jerry Dennis, with illustrations by Glenn Wolff. Jerry Dennis is the author of The Living Great Lakes, A Walk in the Animal Kingdom, The Bird in the Waterfall, and many other books. Visit him at www.JerryDennis.net, and read all of his MOTHER EARTH NEWS posts here.
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