Two decades ago, more than 1 million would arrive in California every winter, clustering on branches in colorful bunches and lighting up the coastal air with their delicate flights.

To see a kaleidoscope of butterflies is to witness one of nature’s most vivid migratory spectacles. A century ago, one California newspaper described a grove of trees with branches breaking under the weight of the western monarch butterflies overwintering in the area. The monarchs, “all twinkling in shade and sunlight, seemed the personification of happiness,” the observer wrote.

Now, monarchs are the personification of something darker, as a species that generations of school children once reared in classrooms in lessons of science and wonder, could soon be gone. This year, only 1,914 were counted overwintering in coastal California. There are more Starbucks locations in California than overwintering monarchs.

North American monarchs, famous for their 2,000-mile annual migrations, are in a freefall. Without help, the western population will almost certainly disappear this century. The eastern population of monarchs, which migrate across the country’s midsection and overwinter in Mexico, is in much the same dire straits.

Stepping back, this decline is no surprise. Since the 1990s, North America’s monarchs have lost about 167 million acres of their summer breeding habitat to agricultural intensification and suburban spawl. Milkweed, the monarch caterpillar’s only food source, has been nearly eradicated from the parts of the Midwest where they were typically born.

The widespread adoption of corn and soy crops that have been genetically engineered for herbicide tolerance has led to a dramatic increase in the use of glyphosate, dicamba, and other herbicides, and has likely wiped out billions of milkweed plants. Large areas of monarch breeding habitat are also planted with cotton, wheat, and other crops treated intensively with pesticides.

Monarchs are also threatened by neonicotinoids and other systemic insecticides used in agriculture, parks, yards, and commercial properties. Neonics are also now one of the preferred or most readily available insecticides used in conventional agriculture, especially for corn, soy, wheat, and other crops. On average, nearly 56 percent of the total planted acres for these crops are treated with such chemicals.

The climate crisis, too, has played a role. It 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 the Joshua Tree National Park will soon no longer support Joshua trees, the International Monarch Biosphere Reserve in Mexico is expected to become climatically unsuitable for monarchs by the end of the century.

The results of these combined changed have been catastrophic. Overall, monarchs’ numbers are down 80 percent in the past two decades, and more than 99 percent among those who overwinter in California.

These butterflies are in a state of emergency for and it’s time to respond. The U.S. Fish and Wildlife Service must protect monarchs by immediately placing them under the Endangered Species Act. In response to a 2014 petition from the Center for Biological Diversity and the Xerces Society, the agency said in late 2020 that protection may be warranted—and then put them on a waiting list.

These kinds of delays too often prove deadly. Indeed, 47 species have gone extinct while waiting for federal protections to kick in.

If we wait, the monarch population will continue to plummet, along with the populations of many other butterflies and bees. The loss of these crucial pollinators will not only threatens our global food security, they will leave a hole in the food web as a number of animals eat monarch eggs, caterpillars, and adults.

Congress should also spend $100 million on monarch conservation. That’s the least we need to cover the cost of restoring one million acres of milkweed and pollinator habitat per year. This will help the butterfly be more resilient to threats from habitat loss, pesticides, climate change, and severe weather.

Landowners and farmers can also play a strong role in this effort by planting milkweed and other pollinator friendly plants in non-cropping areas such as grazing lands, field margins, and yard and garden areas.

In addition, the recently introduced Monarch Action, Recovery and Conservation of Habitat Act of 2021 (“MONARCH” Act) would provide $12.5 million a year to support on-the-ground conservation projects to stabilize and save the western population of monarch butterflies.

By advancing these measures, along with a concerted effort to protect the migratory pathways of monarchs, we can start pulling them back from the brink of extinction. Congress and the Biden administration must do right by monarchs, and act boldly and quickly.

Otherwise, we risk allowing monarchs to slip through our fingers and vanish forever.