Monarch butterflies are as American as apple pie, having once been found in backyards across the country. 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.


The monarch plays a unique and prominent role in the imagination of our country, especially considering it's an insect. These creatures are ambassadors of nature in people's gardens and symbols of summertime outdoors.

Yet these butterflies, once a familiar sight, are plummeting toward extinction due to landscape-scale threats from pesticides, development and global climate change. That's why the Center is working hard to win them protection under the U.S. Endangered Species Act.

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.”

In 2017 the annual March count of monarchs "overwintering" in Mexico's mountain forests — where 99 percent of the world's monarchs migrate for the winter — showed that numbers had fallen by 27 percent from the previous year's count and by more than 80 percent from the mid-1990s. That drastic decline was attributed in part to more extreme winter storms that killed millions of monarchs the previous March. Monarchs need a very large population size in order to be resilient to threats from severe weather events, pesticides and climate change.

In 2020 the yearly count of overwintering monarchs showed an even more dramatic decrease of 53% from the previous year’s count. The numbers are now well below the threshold at which government scientists predict the migration could collapse.

The western monarch population, which overwinters in California, is in even greater peril. Numbering some 1.2 million in the 1990s, it declined to fewer than 2,000 butterflies in the 2020 count. This is way below the extinction threshold estimated by scientists and has to be turned around soon if the species is to be saved.

The heart of the monarch's range is the midwestern Corn Belt, where most of the world's monarchs are born on milkweed plants growing in agricultural fields. Because of the ubiquitous spraying of Roundup on corn and soy that have been genetically modified to resist herbicides, the monarch is in bad trouble in the core of its range, where its sole host plant, milkweed, is disappearing. In a one-two punch, climate change is undermining the stable weather conditions and predictable flowering seasons that monarchs need to complete their migration. Climate change also threatens these butterflies' overwintering habitat in the mountain forests of Mexico. Just as Joshua Tree National Park will soon no longer support Joshua trees, the International Monarch Reserve in Mexico is expected to become climatically unsuitable for monarchs by the end of the century.


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. That December the U.S Fish and Wildlife Service declared the species may warrant protection, triggering an official review of the butterfly's status that, by law, was required to be completed within 12 months. Since by March 2016 the Service still hadn't issued a final decision, the Center for Biological Diversity and Center for Food Safety filed a lawsuit, which resulted in a legal settlement requiring the agency to decide on protection.

Unfortunately the Service's decision, announced in December 2020, was that the monarch's protection was "warranted but precluded" — meaning that although its scientists found that it needed Endangered Species Act protection, that protection was being postposed indefinitely, with no safeguards for the species in the meantime.

And this beautiful butterfly is still declining. With the monarch population well below the threshold at which government scientists predict the migration could collapse, in March 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 this familiar butterfly, along with the decline of many other butterflies and bees, threatens the wellbeing of people as well, because the food security of humans is dependent on the ecological services that pollinators provide.  History shows a tragic record of the unexpected decline of abundant and widespread species. Complacency and false-positive assumptions about the resiliency of once-common species can have tragic consequences when timely action is not undertaken to safeguard their populations. The migration of the monarch butterfly is at risk of being lost unless humans take rapid action to protect it.

The Center is also working hard to save monarchs (and all other native pollinators) 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.