You see them especially in late summer, the elegant monarch butterflies, with their large vari-colored orange and black wings fluttering by on their way south. They’re a fixture of the North American ecology, a common sight that's becoming less and less common, as it happens.
Researchers say that in recent years their numbers have been cut in half, due to habitat destruction both here on their summer ground and in Mexico where they overwinter.
Monarchs lay their eggs on milkweed plants, Only that species will do for this purpose. And the milkweed is in decline because of genetically-modified field crops. Farmers spray these field with herbicides that the crops are resistant to. Weeds, among them the milkweed plants that were once common in such fields, are wiped out.
On their winter ground, in central Mexico the trees on which they perch in great clusters are being cut down.
“It’s clear we’ve lost an awful lot of habitat, mostly over the last ten years,” says Orley Taylor, who heads “Monarch Watch,” based in Lawrence, Kans. “The population has declined significantly.”