The Earth Is a Machine

Take, for example, the story of the monarch butterfly. This is a beautiful orange and black insect whose wings fold into gently curved triangles when they alight. Native to the Americas, monarchs travel on an annual migration through Canada, the United States and Mexico, pausing along the way to gather in enormous flocks of tens of thousands of butterflies. They gather in such incredible numbers that trees appear to be draped in orange-and-black leaves,SRRL50F Main Specification manufacturers and exporters which upon closer examination resolve themselves into fluttering wings.  This season, however, the great monarch migration to Mexico has become a shadow of its former self. Hundreds of thousands of butterflies used to descend on the cool mountains of central Mexico, but last year only 60,000 came.

This year only 3000 arrived, a week late. Environmental scientists are warning that the insects may be headed rapidly for extinction. What happened?Think of the monarch butterflies' population as the output of a machine process that has gone wrong. To understand that process, scientists have had to observe the butterflies and their environments for decades. It was only in the 1970s when Canadian entomologists Fred and Nora Urquhart discovered something incredible about these butterflies. Their migration spans 3 to 4 generations, with each new generation completing only part of the circuit between Canada and Mexico.

The butterflies who begin this incredible cross-continental migration in Canada will never make it back – only their great-grandchildren will.Along the migration route,buy Wheel loader SRRL50F-III from China each generation settles in a preferred egg-laying area full of milkweed, which is the only kind of plant their larvae can eat. In a sense, these animals are living out the scenario that so many science fiction writers have imagined in stories of generation ships. Each cohort goes on a journey from which they will never return home. But their offspring will eventually complete this dramatic quest.What anchors this epic flight is the environment. Specifically, the butterflies require milkweed, without which they cannot return to their ancestral homes because they can't reproduce.