Monarch butterflies are important culturally and ecologically across North America. Generations of schoolchildren have reared monarchs in classrooms, watching in wonder as striped caterpillars transform into large orange-and-black adult butterflies. The monarch's multigenerational migration is legendary — a journey of more than 2,000 miles from Mexico to Canada, undertaken by animals weighing less than a single gram.

Monarch butterfly
These iconic beauties have plummeted by 80 percent in the past 20 years. We're working hard to protect them.
Please help us save monarch butterflies now.


In the United States and southern Canada, monarchs are ambassadors of nature in people's gardens and symbols of summertime outdoors. In Mexico, the beloved butterflies arrive for the winter during Day of the Dead celebrations where they symbolize the souls of the departed.

Yet these butterflies, once a familiar sight, are plummeting toward extinction due to landscape-scale threats from pesticides, development and climate change. That's why the Center is working hard to win them protection under the U.S. Endangered Species Act and to safeguard them from pesticides.
In monarchs' overwintering groves, there were once so many butterflies that the sound of their wings was described as a rippling stream or a summer rain. Early newspaper descriptions described branches breaking under the weight of so many butterflies and depicted the masses of monarchs as “the personification of happiness.”

Historically monarchs across American prairie and grasslands would have numbered in the billions. In the late 1990s the clustered butterflies covered 45 acres of fir trees in their overwintering forests in Mexico, but over the past two decades monarchs have declined by 90% and in 2021 there were only 5 acres of eastern butterflies. Scientists estimate there needs to be a minimum of 15 acres of butterflies to be out of the danger zone of migratory collapse.

The monarch population west of the Rocky Mountains, which overwinters in California, is in even greater peril having declined by 95% over two decades. Numbering some 1.2 million in the 1990s — and having a brush with complete collapse in 2020 — in 2022 the butterflies rebounded to 247,000, eliciting a collective sigh of relief from butterfly enthusiasts.  

Across their range, monarchs are threatened by pesticides, climate change, ongoing suburban sprawl, and fragmented and poisoned habitats as they navigate their way across the continent. They need a helping hand from the government, businesses and concerned individuals.



We took our first big action for monarchs in August 2014, when the Center and allies petitioned to protect monarchs as "threatened" under the Endangered Species Act.

Unfortunately in December 2020, the U.S. Fish and Wildlife Service announced that monarchs' protection was "warranted but precluded" — meaning that although its scientists found that monarchs needed Endangered Species Act protection, that protection was being postponed indefinitely, with no safeguards for the species in the meantime.

And these beautiful butterflies are still declining. With the monarch population well below the thresholds at which government scientists predict the migrations could collapse, in 2020 the Center and more than 100 other groups called on Congress to significantly increase funding to $100 million per year to help conserve monarch butterflies and their habitat.

Monarchs' decline is a harbinger of widespread environmental change. The plummeting population of these familiar butterflies, along with the decline of many other butterflies and bees, threatens the wellbeing of people too, since the food security of humans is dependent on the ecological services that pollinators provide. Monarch butterflies and their epic migration could disappear unless people take rapid action to protect them.

The Center is also working hard to save monarchs and all other imperiled species from pesticides like glyphosate and dicamba through our Environmental Health program.

Check out our press releases to learn more about the Center's actions for monarch butterflies.

Monarch butterfly photo courtesy Flickr/Debbie Long.