The Lighter Side of Wind

With all the damages from hurricanes, the wind certainly gets a bad rap. Looking at all the damages caused by Floyd and friends, it is hard to imagine any benefit from even a light breeze. But there are a large number of life forms which depend on just such a light wind. And what may look like empty wind blowing around over your head, may in fact, be teeming with life!

The wind is a major distributor of plant and insect life on Earth. Because plants are sedentary, they had to be creative as they evolved to ensure their survival, and so they 
quickly put wind to use. Dandelions can  ride on their beneath that fluffy down, can drift for hours on a breeze. The tiny seeds of cattails and bulrushes have been carried for hundreds of miles over open ocean to colonize remote lands!

A study of air samples was done over Louisiana. One sample, 5000 feet above the surface, contained seeds from daisies, cottonwood trees, five kinds of grass and four species of thistle! But the same sample yielded more than just plant seeds.

When we look up into the sky, we see the usual flocks of birds, leaves floating lazily along in the breeze and the occasional butterfly but it mostly seems to be an empty place. But this is not the case. During summer, a cubic mile of air over temperate regions on the planet contain as many as 25 million assorted insects, spiders and other assorted animals suspended or drifting in the winds!

Life on the breeze is not just limited to the temperate regions either, though that it where is is most abundant. High up in the ice fields of Mount Everest there lives a species of jumping spider that probably holds the record for highest elevation as a permanent resident. At first, scientists were baffled as to how any creature could survive in such an environment, yet this spider seemed to thrive. Imagine the shock and surprise of the scientists when they discovered that food virtually fell from the sky, and all the spider had to do was patiently wait for it! On a daily basis, countless flies, aphids, beetles, ants, midges and mites, none of which were indigenous to that area, were deposited upon the icy grounds. These animals were swept n updrafts to these high altitudes where they perished and the spiders thrived.

In the 1930's a pair of entomologists in England used a kite and specimen net to sample the air at heights from 150 to 2000 feet. They gathered 839 insects which included plant lice, small flies, aphids, thrips and parasitic wasps. These were mostly light bodies creatures poorly designed for flight. At about the same time, an entomologist in the US flew over 1400 flights in a biplane equipped with screens between the wings. In the skies over Louisiana he collected over 30,000 insects from over 700 species from altitudes of 20 to 15,000 feet. He also found a huge collection of seeds, pollen, spores, bacteria and other minute living things. In 1963, biologist L.W. Swan named this airborne bestiary the "aeolian zone." It was named for Aeolus, the Greek god of the wind.

Most of the animals carried aloft are probably unwilling travelers, but some are not. Many species of spiders use the wind to transport their newly hatched babies to new homes. On warm sunny days, the baby spider will climb to the end of a twig, or a barn door and pointing its abdomen into the air, it lets loose a long strand of silk.  The little spider might release six to ten feet of silk until it is caught by the wind and transports the spider aloft. Such journeys could be long, baby spiders have been captured as high as  seven miles above the ground, and have been carried hundreds of miles from land, where they have been deposited on the masts of ships. A few species of spiders continue to take advantage of the air transportation system even when they are adults.

In our area, we have an accomplished aeronaut in the dreaded pest the gypsy moth. While in the caterpillar stage, this creature releases  silken strands which allow it to become airborne. Even the hairs on the caterpillar are hollow to increase its buoyancy, and  this animal can travel upwards to 2000 feet and across miles of countryside. This is one of the reasons these pests are difficult to control.

The next time you are out battling the plant and animal pests in your yard and garden, and you sit back on your heels and relish that cooling breeze, beware, there's more than meets the eye!