Want To Save Monarch Butterflies? Start Planting Milkweed

May 18, 2017

If Monarch butterflies are going to stay off the endangered species list, they need more to eat. And it’s up to us to feed them.

That’s the conclusion of a new study by the U.S. Geological Survey.  One big problem: monarch caterpillars are extremely picky. They can only eat one thing — milkweed.

Monarchs used to feast on the milkweed growing in corn and soybean fields. But then the herbicide glyphosate began to be widely used on genetically modified corn and soy fields. As a result, almost all of the milkweed is gone.

Monarch caterpillars eat only one thing: milkweed. And they need about 1.8 billion more stems of it to survive.
Credit Sid Mosdell / Flickr

Now monarchs are relying on milkweed in other places, but there’s just not enough of it. Wayne Thogmartin, an ecologist with the USGS, estimates monarchs need 1.8 billion more stems of milkweed. So, he says, we should plant more of it. But if you do plant milkweed in your backyard, he says you should go for native varieties and avoid any milkweed that’s treated with neonicitinoid pesticides, because they can kill monarch caterpillars. Lowe’s and Home Depot both say they’re working to phase out the use of those pesticides in their plants within a few years.

The monarch butterfly population has dropped by about 80% since the mid-90s. And there’s been so much concern about the steep drop that a few years ago, the Center for Biological Diversity and other groups petitioned the U.S. Fish and Wildlife Service to protect it as a threatened species under the Endangered Species Act. The review process is supposed to take a year, but Brett Hartl, government affairs director with the Center for Biological Diversity says it often takes longer. They filed a lawsuit to get the Fish and Wildlife Service to act. But they’re hoping that by 2019, the government, nonprofits and regular people will be able to do enough work on monarch conservation that the species won’t need to be listed as “threatened.”

Hartl says early efforts to plant milkweed and preserve habitat have been good, but monarchs need more investment — something  like the half a billion dollars the federal government has spent out west to keep the sage grouse off the endangered list.  And Hartl wonders if the federal government has the appetite to make sure monarchs have the milkweed they need to survive. The Trump administration’s proposed budget plan suggests big cuts at the U.S. Fish and Wildlife Service, the Department of the Interior and the Department of Agriculture. “That obviously has effects even on things like monarch butterflies,” he says.

Reporting by Rebecca Williams / Michigan Radio.

Find this report and others at the site of our partner, Allegheny Front