The Corn Belt Tightens the Belt on Monarchs

One of my most vivid childhood memories from Iowa’s corn country is watching clouds of monarch butterflies dance around the milkweed patch by our back steps and finding caterpillars on the leaves. My brother and I raised them, as many kids do. They were the first butterfly I learned to identify, and just knowing their name made them more special.

Even as an adult, I watch eagerly for monarchs all summer. On a recent hike with local naturalist and author John Bates, he philosophized that “monarchs might be the next passenger pigeon.”  Indeed, their population has been in decline since 1997 (from a high of about a billion individuals, down to just 35 million) and a recent study warns that there is a greater than 5% chance that they will experience “quasi- extinction” (less than 1000 individuals) within a century.

In the past, it was easy to blame our southern neighbor for the declines. Illegal logging with mafia-like techniques in the mountainous butterfly preserves of Mexico was a major problem, but it has largely been addressed by the Mexican government. There is still more to be done with supporting the local economy so that the locals won’t need to extract resources from the protected forests, but the biggest challenge to the monarch’s struggle for survival is no longer across an international border. It is right here in the US, in the every-more-productive Corn Belt where I grew up.

The incredible migration that monarchs are beginning just now will culminate next spring in a flurry of reproduction. The butterflies that fly south from Wisconsin and Minnesota this September will overwinter in the remote oyamel fir tree forests in the mountains west of Mexico City. In early spring, those same monarchs will head north again – hoping to lay their eggs on spring-fresh milkweed plants in Texas before they breathe their last butterfly breath.

But what if there isn’t any milkweed? Drought, cold weather, and habitat loss have all been recent issues. And the challenges continue as generations of monarchs leap-frog north into the Midwest – into the infamous Corn Belt. A majority of monarch butterflies on the Mexican wintering sites are born in the Corn Belt. Since the first genetically modified (GMO), herbicide resistant soybeans were introduced in 1997 (with GMO corn following shortly), there has been an 80% decline in milkweed in the Midwest, and a concurrent 81% decline in monarchs. In Iowa, one biologist estimates there has been a 98% reduction in milkweed on the landscape.

 “What we’re seeing here in the United States is a very precipitous decline of monarchs that’s coincident with the adoption of [herbicide-resistant] corn and soybeans,” says Chip Taylor, founder of Monarch Watch.

While GMO products have garnered support among some scientists for their apparent food safety, the changes that GMOs have caused in our farming practices and the subsequent habitat loss for many organisms (not just monarchs) are a significant bit of collateral damage. More GMO crops – some resistant to several types of herbicides—are in the development pipeline.

It’s not just GMOs and glyphosate herbicides. Farming practices have changed a lot since my Grandpa Warren hunted pheasants among fencerows in central Iowa. With corn prices soaring, bigger equipment, and bigger farms taking the lead, and subsidies for ethanol taking the place of the Conservation Reserve Program (CRP) subsidies, more of the land is under cultivation than ever before.

“Overall, genetically modified, herbicide-resistant crops have increased the current, and predicted future, extinction probability of monarch butterflies in eastern North America,” agree a team of international scientists writing for the Journal of Animal Ecology last year. They found that, while winter mortality is still an issue to contend with, the loss of milkweed in the Corn Belt is the greatest factor precipitating monarchs’ population declines. That same article admonishes that addressing these challenges is “the highest conservation priority.”

There is some good news. Favorable weather and efforts by back-yard conservationists like Eve Depew and Cec Peterson have helped. Chip Taylor just wrote in his most recent Monarch Population Status blog post at MonarchWatch.org, that “The number of eggs found …now leads me to suspect that the migration through the upper Midwest will be better than any migration seen since 2011.” A year of population growth will be very welcome.

Habitat loss is the biggest problem, and you can help. Every extra back-yard milkweed plant and un-sprayed flower garden could host one more caterpillar, and provide nectar for hundreds of pollinators. Getting the Department of Transportation, the Forest Service, and the National Park Service involved can offer access to even more acres.

But gardens like these “are not going to make up for 25.5 million acres of additional corn and soybeans,” says Chip. Large conservation efforts – and sustainable farming practices – also are necessary. You can help there, too, by choosing carefully at the grocery store, by supporting the organizations doing good work, and by letting your representatives at all levels of government know that you value conservation efforts. Several concerned groups banded together last year to ask that the monarch butterfly be listed as “threatened” under the Endangered Species Act, which would increase funding and research into their recovery.

Should we do all of that work, and make all of those sacrifices just to save a single species of beautiful, amazing butterfly? No! We should work to save the monarch because in doing so we will also be saving ourselves, our planet, and the futures of kids like Eve.

Monarchs are experiencing steep population declines, mostly due to farming practices in the Corn Belt. Why should we care? For the futures of kids like this one! (Who just happens to be my nephew Derek, from the heart of corn country in central Iowa.) Photo by Larry Stone.