Delicate Aviators' Amazing Odyssey
September's Monarchs Embark on Nature's Most Incredible Migration
By Lowell Washburn

As the days grow shorter and fall approaches, newly emerged monarch butterflies become restless. Although the bright orange- and black-winged insects currently visiting backyard flowerbeds may appear identical to those seen earlier in the summer, they are biologically different from all others. The group of adults currently flittering about are so unusual that scientists give them a special name-this year's final crop of young are the annual super generation.

Unlike their predecessors, whose entire life cycle could be measured in mere weeks, super generation monarchs complete a three-thousand-mile-long migration marathon, acquire the remarkable ability to halt aging and then stay alive for more than eight months-the rough equivalent of a human living six centuries.

The annual cycle begins high in the remote volcanic mountains of central Mexico. With the arrival of spring, monarchs that hatched the previous summer in Canada and then migrated to Mexico last autumn, suddenly respond to the irresistible call to move north. But their second migration will be brief and adults will never see their Canadian homeland again. Arriving on the plains of Texas, the ancient insects pause to mate, lay eggs and die...

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