The Canary in the Corn Field | WYPR

The Canary in the Corn Field

Sep 23, 2014

In the late 1990s, farmers across the U.S. began planting a different kind of crop.  About 90 percent of farmers started raising corn and soybeans that were genetically modified to tolerate an herbicide called glyphosate or Roundup. That was bad news for monarch butterflies, the iconic symbols of summer, whose populations have plummeted by 90 percent since then.


Genetically engineered “Roundup-ready” crops are designed to be sprayed with the weed killer glyphosate and tolerate the chemicals and live, while other plants around them die. 

But as the weeds have disappeared from many of America's fields over the last 15 years, so have the monarch butterflies.  Monarchs are well known to many school children because their lifecycle is taught in the classroom.  The butterflies are also famous for their spectacular multi-generational migrations from Canada and the Upper Midwest to Mexico and back.

As late as 1996, scientists estimated that a billion monarchs filled the skies of the U.S. east of the Rocky Mountains.  This year, the monarch count is down by 97 percent, to an all time low, and this decline appears to be part of a trend, according to Tierra Curry, Senior Scientist at the Center for Biological Diversity, a nonprofit conservation organization.

“The decline is being driven by the loss of monarch breeding habitat in the Midwestern United States. And that has come about because Monarchs are dependent on milkweed," said Curry. "Milkweed is a native flower and it’s the only food that monarch caterpillars will eat. And so because we’ve started planting so many genetically modified corn and soybean crops, we are using more Roundup.  And so we are spraying so much Roundup now that we are eliminating the milkweed, and by eliminating the milkweed, we are eliminating the monarch’s host plant.”  

In an attempt to save the monarch and its host plant, the Center for Biological Diversity has  petitioned the U.S. Fish and Wildlife Service to grant monarchs protections as a threatened species under the Endangered Species Act.

The petition also outlines other potential contributors to the Monarch’s decline – including development, logging, and climate change.  But Threat No. 1, according to the petition, is Roundup.

The Monsanto company, which manufactures Roundup, declined to be interviewed for this radio program.  But a Monsanto spokeswoman provided a written statement that said, in part:  “The challenge is complicated.  Monarchs need milkweed to survive.  It is the only plant monarch caterpillars will eat.  But for farmers, milkweed is a weed. It competes with crops in the field for water, soil and nutrients….   Saying a species is closing in on extinction when most disagree or calling on government to list monarchs as threatened species under the Endangered Species Act makes for a great news headline.  It doesn’t do anything to help solve the problem."

Lincoln Brower, a biologist at Sweetbriar College in Virginia who has been studying monarchs for a half century, disagrees,, saying over-use of Roundup is almost certainly a major part of the problem.

“We’ve referred to the Monarch as the canary in the corn field," Brower said.

He said people know about the deaths of monarchs – because monarchs are highly visible. But there are likely scores of other lesser-known insects and native plants that are quietly vanishing  because of the increasing use of glyphosate or Roundup. The herbicide is sprayed not only on farm fields, but as a weed-killer along roads and under electric lines. 

“Most butterflies and many species of insects feed on the leaves of wildflowers and native plants and shrubs and so forth. There is a huge array of species that are dependent on these naturally growing wild plants," Brower said. "And the problem with this glyphosate is that it kills everything. It sterilizes the soil. I have pictures of rows of corn and soybeans there’s not a blade of grass or anything growing in those fields.” 

In case you think this is just a few biologists worried about this, President Obama in June issued a memorandum that described the loss of butterflies as part of worrisome decline in a variety of pollinators, including bees and bats.  Without pollinators, we would lose many fruits, nuts, and vegetables -- and about $15 billion a year from our agricultural economy, according to the White House.   President Obama ordered EPA to "assess the effect of pesticides...on bee and other pollinator health and take action, as appropriate, to protect pollinators."

Part of the solution is likely to use less herbicides and pesticides and switch to more organic farming.  Along our highways, we should stop spraying chemicals and allow more wildflowers and native plants flourish.  After all, what might look like weeds out our car windows might feed the butterflies we cherished when we were children, but now miss.