Monarch Facts

The migration and importance of monarchs

Monarch butterfly on milkweed
  • Monarch butterflies are one of nature’s great wonders. The monarch’s annual migration is one of the most awe-inspiring on Earth. Each fall, hundreds of millions of these striking black-and-orange butterflies take flight on a 3,000-mile journey across the United States and Canada to wintering grounds in Mexico’s Sierra Madre Mountains. (source)
  • Monarch butterflies pollinate many different kinds of wildflowers. (source)

Monarch populations are plummeting

  • The monarch butterfly population has declined to 2.91 hectares—almost 30% less than last year’s population. The monarch population has been in steady decline for the past 20 years—reaching a high of over 20 hectares in 1997 and plunging to 0.67 hectares in 2014. (source)
  • Two decades ago, nearly 1 billion wintering monarchs blanketed the mountain forests of Mexico. Today, that number has dropped by as much as 80 percent. (source)

Herbicides and milkweed

  • Heavy use of an herbicide called glyphosate (marketed by Monsanto as Roundup) has greatly diminished milkweed, a native wildflower that is the sole food source for monarch caterpillars and the only plant on which they lay their eggs. (source)
  • As milkweed disappears, monarch populations have also plummeted and the annual migration of monarchs to Mexico is in danger of collapse. (source)
  • EPA recently re-approved the registration for Dow’s Enlist Duo, a combination herbicide designed to kill milkweed. (source)


  • Much effort has gone into planting milkweed throughout the continental US in the last several years. (source)
  • But this year’s monarch butterfly population demonstrates that we need to do much, much more if we are going to be successful at building the monarch population back up again to secure numbers. (source)
  • Planting milkweed will not be enough. We also need to curb the use of pesticides that are eliminating milkweed in the first place and come up with sustainable solutions—not just for butterflies, but for farmers and our public health. (source)

How NRDC is helping secure a healthy future for monarchs

  • NRDC envisions a future where monarch populations across North America are healthy and resilient. To achieve this, we’re working at the federal, state, and international level to secure limits on the use of toxic herbicides and create new milkweed habitat. (source)
  • We’re taking legal action against the U.S. Environmental Protection Agency to win restrictions on toxic herbicides, such as glyphosate, that are killing off native milkweed. (source)
  • And we’re calling on agribusiness companies to withdraw their toxic products. At the state level, we’re working with officials to plant new milkweed habitat along the monarch’s migration route. (source)
  • And we’re leveraging international pressure by petitioning UNESCO’s World Heritage Committee to upgrade its protection of monarch wintering habitat in Mexico. (source)

Recent NRDC milestones in fight to save monarchs (source)

  • Worked with the Tollway in Illinois, a key agricultural state, to plant milkweed along hundreds of miles of roadsides and passed legislation to establish a monarch butterfly license plate that will fund a statewide milkweed planting program.
  • Mobilized more than 113,000 of our Members and activists to sign a petition demanding Dow AgroSciences remove Enlist Duo from the market.
  • Generated an outcry against Enlist Duo in Congress that included signatures from 32 lawmakers calling on the EPA to take a closer look at the devastating health and environmental impacts of this herbicide.
  • Ramped up international pressure, including 50,000 petitions from NRDC Members and activists, on the UNESCO World Heritage Committee to declare the Monarch Butterfly Biosphere Reserve in Mexico as “endangered” due to the destruction of monarch habitat in the United States and Canada by glyphosate. In response, UNESCO launched a formal evaluation of the request.

NRDC & Monarch Watch planting milkweed

  • Monarch Watch is a nonprofit educational outreach program based at the University of Kansas that focuses on the monarch butterfly, its habitat, and its spectacular fall migration. NRDC partners with Monarch Watch to plant milkweed plants at schools, churches and garden clubs to help save North American monarch butterflies.
  • Monarch Watch has been distributing the 100,000 milkweed plants featured in this Monarchs for Moms campaign for planting on tribal lands and other locations along the monarch’s migration route since 2016.
  • NRDC’s Green Gifts program also supports Monarch Watch to distribute free milkweed plants to schools and educational nonprofits.