by Sue Halpern
The butterfly ambling around the yard was orange and black, and there was no mistaking it for anything but a monarch. My daughter saw it first, and followed its course from the stand of milkweed at the edge of our driveway as it tacked over the gravel, east to west to east again, and headed straight for me. "He likes you," my daughter said, though she is eight, and knows better than to assign human emotions to a bug.
Still, the monarch was circling my shoulders in ever smaller arcs, like a plane about to land, until it finally glided to a stop on the top of my sneaker, which was blue. The monarch unfurled its proboscis and poked around futilely. "He thinks it's water," my daughter said, "or a flower."
Both were good guesses. It was August in the mountains of upstate New York and that monarch would soon be embarking on an improbable journey. It would fly 3,000 miles, to the flank of a steep, 50-acre oyamel fir forest high in the mountains of Mexico where it would wait out the winter. Water and fuel and wind would get it there, and more than a little luck avoiding the long reach of avian predators and storms and cars and disease and the deadly pollen of genetically modified corn on monarch larvae.
The corn pollen threat was new. A few years ago, corn that had been genetically engineered to kill an agricultural pest called the European corn borer was found by chance – after it had been approved by the EPA and was already in production – to be lethal to monarch caterpillars as well. Though it appears that the current strain of GM corn may be significantly less toxic to monarchs, it is unclear what its "sublethal" effects are, or will be, or when we will know. In the meantime, millions of monarchs manage to find their way to Mexico each year.
While that would be remarkable enough – an insect that weighs less than a gram flying thousands of miles to the smallest of spots on the map – what's even more so is that it takes four or five generations to complete the round-trip. That means that no monarch that migrates to Mexico has ever been there before. And nobody, not even the scientists who have devoted their professional lives to this insect, knows how they do it. Not one has been able to prove how monarchs orient and navigate and cross the borders of three countries to end up in a forest so full of monarch butterflies that the beat of their wings is as loud as surf cresting rocks, and the tree branches bow to the ground from their weight, and the sky darkens as they edge out the sun. And though this is the age of the human genome map and the unifying theory of physics, the monarch presents a scientific conundrum that may never be solved.