Monsanto's newest scheme is very bad news for monarch butterflies

Jerry Holt, Star Tribune

Jerry Holt, Star Tribune

Minnesota may soon be a state without its state butterfly.

That’s according to a report released last week by the Center for Biological Diversity, which found that by 2019, a weed-killer designed for use on genetically modified cotton and soybeans will be used on over 60 million acres of the monarch butterfly’s migratory habitat — with dire implications for the already imperiled insect.

The weed-killing chemical, called dicamba, is extremely harmful to the milkweed monarchs depend upon for reproduction. Milkweed is the only plant monarchs will lay their eggs on, and is the sole food source for the monarch caterpillar. Each spring, coinciding with the emergence of milkweed, monarchs migrate north, from their winter habitat in Mexico, back to northern climates like Minnesota, laying their eggs along the way.

But fewer and fewer monarchs are making it back to Minnesota. In 2015, the measured population of monarch butterflies in winter had fallen to 42 million, an 80 percent decline from average populations the previous two decades. That figure rebounded some in 2016, to 150 million, but fell again in 2017, to closer to 100 million. 

The Center for Biological Diversity's report says long-term population trends reveal an "ongoing risk of extinction for America's most well-known butterfly."

Dicamba has been around for decades, but its use surged in 2017 as a solution to weeds which have become resistant to glyphosate, commonly known as Roundup -- also a Monsanto product.

In 2016, the Environmental Protection Agency approved the use of dicamba on organisms genetically engineered to be resistant to the weed-killer. Monsanto has since introduced dicamba-resistant cotton and soybean seeds which debuted in the 2017 growing season. By 2019, U.S. farmers are projected to douse their fields with 57 million pounds of dicamba annually, according to the report.

Those numbers are already alarming to scientists concerned about the monarch’s chance of survival. Also concerning is that dicamba is toxic enough to directly harm monarchs, according to Aimee Code, pesticide program director for the Xerces Society for Invertebrate Conservation.

To make matters worse, dicamba is highly drift-prone, sometimes straying a half-mile from where it was sprayed -- or turn from a liquid to gas, and travel through the atmosphere -- posing a threat to milkweed, which often grows in the margins between agriculture fields. The report estimates an additional 9 million acres of monarch habitat will be threatened by drift by 2019.

Drifting dicamba damaged 3.6 million acres of soybeans last year, according to a report by the University of Missouri. The potential for crop damage from the volatile herbicide puts pressure on farmers who don’t use Monsanto's chemical-resistant seeds. Many feel forced to buy the seeds from Monsanto and expand the use of dicamba. Monsanto expects 40 million acres of its dicamba-tolerant seeds to be planted this year, double the total from 2017.

Concerns over dicamba have led many states to crack down on its use. Last December, the Minnesota Department of Agriculture announced several restrictions on the herbicide. Farmers are no longer allowed to spray after June 20, or when the temperature reaches 85 degrees. Missouri and North Dakota have also restricted dicamba use and Arkansas has completely banned it. It may not be enough for the monarchs, however.

“There is no scenario where using a pesticide at this magnitude will not have serious consequences for the monarch butterfly, its habitat and the ecological health of vast areas of our country,” stated the report.

Some Minnesotans are taking matters into their own hands to help the monarch. Save Our Monarchs, a Minnesota-based nonprofit, works to get people planting milkweed all over the country. Director Ward Johnson grew up in western Minnesota, and remembers seeing monarchs everywhere when he was a kid. He founded the organization in 2014 and has since distributed over 2.5 million milkweed seed packets across the country.

“The key is to get people off their ass, and get out and plant milkweed,” he said. “No milkweed, no monarchs.”

The monarch was adopted as Minnesota's state butterfly in 2000 at the urging of a fourth-grade class at Anderson Elementary School in Mahtomedi.

Then-state representative Harry Mares, a Republican from White Bear Lake, took up the classroom's issue, and sponsored a bill to recognize the monarch. As Mares later explained: “A lot of people have an early introduction to the magical world of nature through the monarch. As we get older it becomes a thread that takes us through science to beauty and aesthetics.”