President Obama, Canadian Prime Minister Stephen Harper, and Mexican President Enrique Peña Nieto will surely discuss cross-border migration when they meet next week in Toluca, Mexico. But people aren’t the only border crossers. The three leaders should also discuss the migration of monarch butterflies, a remarkable natural phenomenon that’s in growing danger of disappearing.
The monarch butterflies that appear in New England during the summer are part of a long, mysterious migration that takes up to four generations to complete. The species winters in a small area of forest in Mexico, not far from where the trilateral summit will take place. But fewer migratory monarchs are wintering there than at any other point in at least two decades. Once, perhaps a billion butterflies blanketed up to 45 acres of forest; recently, the World Wildlife Fund estimated that butterfly cover was down to just 1.65 acres and maybe 35 million monarchs. All three countries are at fault. Overlogging for forest has destroyed their habitat in Mexico, while agricultural herbicides in the United States and Canada have wiped out milkweed, the sole plant that the monarchs’ larvae will eat.
Unlike migratory birds, the butterfly is not protected by any international treaty. But a joint strategy is needed. In 2010 the White House hosted the president of Mexico at a state dinner with artificial monarchs hanging from the ceiling. It would be a shame if Obama, Harper, and Peña Nieto paid no heed to the fate of the real thing.