Late Migration

monarch-yellow-zinnia-2Every monarch in the world is hatched on the leaf of a milkweed plant somewhere in the continental United States, and almost all of them spend winters on fir-covered mountains in central Mexico, in clumps so thick that tree branches can crash to the forest floor from their weight.

But this March, a storm brought such shattering winds and rain to their Mexican wintering grounds that millions of butterflies died before they could return to the US to breed. And the milkweed the survivors were looking for—once ubiquitous on American roadsides and in vacant lots and at the stubbled edges of farms—are mostly gone now, too, a casualty of the herbicides that go hand-in-glove with genetically modified crops. [Continue here.]