MEXICO CITY — The annual migration to Mexico of millions of orange-and-black monarch butterflies is one of the nation’s cherished rituals. But it could come to a virtual halt if the insect’s natural habitat is not urgently salvaged.
That is the conclusion of a long list of scientists, artists and environmentalists who are calling on the leaders of Mexico, the United States and Canada to act swiftly to protect butterfly breeding grounds. President Obama, Mexican President Enrique Peña Nieto and Canadian Prime Minister Stephen Harper are to meet in Mexico next week to discuss economy, trade and other issues.
Although the number of butterflies that travel thousands of miles across North America to Mexico has been declining fairly steadily for years, the migration has never been in more danger than now, the activists say.
Blame has always been put on rampant illegal logging in Mexico that destroys the oyamel fir forests where the insects alight and spend the winter. Increasingly, however, activists say blame must be placed on eradication of the milkweed plants in the United States, where the butterflies lay their eggs and where monarch caterpillars eat.
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“It is ecological genocide,” said Homero Aridjis, a prominent Mexican poet and advocate for the butterfly. “By killing the plant, you are killing the monarch butterfly. If they don’t stop the destruction of the milkweed, in a few years the migratory phenomenon could collapse.”
Especially in the U.S. corn belt, the planting of genetically modified, herbicide-resistant corn and soybean varieties has grown dramatically. The insecticides that are used, especially glyphosate, destroy all other plant life, including the milkweed — the only plant eaten by monarch caterpillars.
In addition, the big money to be made from ethanol has led to increased planting of corn in previously marginal areas that would have been covered in milkweed. Activists warn that the disappearance of the monarch bodes ill for worldwide ecology, akin to the loss of bees.
“The onslaught of chemical agriculture … is altering the entire food chain,” said Lincoln Brower, a research professor of biology at Sweet Briar College in Virginia and one of the world’s top experts on the monarch. “I think the extraordinary, rapid decline of the monarch butterfly is the canary in the coal mine.”
In a letter to the North American leaders written by Aridjis and signed by more than 100 well-known academics and others, including two Nobel laureates, several possible solutions are proposed, including the planting of milkweed on the sides and medians of the vast network of U.S. roads that generally follow the butterflies’ migratory route.
For the past 20 years, the activists say, the average area occupied by butterflies in the western Mexico forests where they arrive annually was 16.6 acres. This year, scientists observed a record-low 1.7 acres, a 90 percent decrease.
“This winter, only seven of 12 traditional sites had any butterflies at all, and only one of those (El Rosario, 0.5 hectares) was substantial in size,” the letter says. Half a hectare is equivalent to 1.2 acres.
Aridjis said Mexico had made progress in stopping large-scale illegal logging but that destructive smaller operations continued.
“As Mexico is addressing the logging issues, so now must the United States and Canada address the effects of our current agricultural policies,” the letter says. “Managing roadsides for native plants, including milkweeds, could be a significant tool to partially offset the loss of habitat.”
Most of the monarch habitat is in the western Mexico state of Michoacan, a violent, largely lawless region dogged by drug cartels and, more recently, a flourishing vigilante movement fighting the traffickers. Many in Michoacan believe the illegal loggers are in cahoots with the cartels.
Aridjis delivered the letter to representatives of the Mexican, U.S. and Canadian governments in Mexico City on Thursday and released it publicly Friday.
In a separate action, the World Wide Fund for Nature similarly urged North America’s three leaders to commit to preserving the monarch habitat, “one of our oldest and most spectacular links.”
The leaders will be meeting Wednesday in Toluca, in Mexico state, a few miles from the center of the butterfly hibernation.
“The combination of threats has caused a dramatic decline in the number of butterflies in hibernation colonies in Mexico over the last decade,” Omar Vidal, WWF director in Mexico, said in a statement. “At 20 years after the signing of the North American Free Trade Agreement, the monarch migration — symbol of cooperation among the three nations — is at grave risk.”
The butterfly migration has long been a huge tourist attraction in Mexico.
Leticia Ramirez Vidal, 36, an architect, went to Ocampo, in Michoacan, two weeks ago to see the butterflies, her first time in more than a decade. The difference, she said, was stark.
“I remember when I went the first time, you reached an area where it was impossible not to step on the butterflies — there were so many, it was a really impressive amount,” Ramirez said. “Now you have to walk and walk just to find places where the butterflies are.”