monarch butterfly among leaves
A butterfly sits on a leaf at Monarch Grove Sanctuary in Pacific Grove, Calif. Monarch populations dropped significantly this year compared to 2023. Nic Coury / Associated Press
monarch butterfly among leaves
A butterfly sits on a leaf at Monarch Grove Sanctuary in Pacific Grove, Calif. Monarch populations dropped significantly this year compared to 2023. Nic Coury / Associated Press

The monarch butterfly’s famed summertime visits to Chicago could be in jeopardy thanks to climate change and extreme weather.

Chicagoans may already see fewer of the graceful orange and black insects this summer.

Researchers in Mexico have observed a steep decline in the butterfly population ahead of its spring migration. Experts now worry those environmental factors could lead to the loss of the insect’s famed migration path altogether.

This winter marked the second-lowest number of migratory monarch butterflies since recordkeeping began in 1993. The pollinator completes the longest known insect migration each year, leaving northern climates in the United States and Canada for Mexico and California every winter. The monarch, the state insect of Illinois, already faces threats such as pesticide use and habitat loss that have contributed to their low migration numbers.

“The loss of the world’s longest migration path would certainly be an indescribable and devastating tragedy,” Lindsay Keeney, conservation director at the Illinois Environmental Council, said in an email. “As climate change accelerates, the species may adapt by shortening the migration path or even staying too long in southern climates where habitat is rapidly declining.”

The annual monarch butterfly count is calculated based on how many acres of land the insects cover when they land in forests west of Mexico City.

Mexico’s National Commission for Protected Natural Areas said the levels of migratory monarchs were 59% lower this January compared to last winter. The monarchs covered about 2.2 acres, compared to 5.4 acres in 2023. It’s the lowest count since 2013, which came in around 1.65 acres.

The significant one-year drop this winter makes experts worry. Aster Hasle, lead conservation ecologist at the Keller Science Action Center, a subsidiary of the Field Museum, said while it’s normal for insect populations to fluctuate year to year, this extreme of a drop is troubling. Abnormally hot, dry conditions this year — a result of climate change — were likely to blame.

Migratory monarchs typically start moving south in August, eventually reaching southern Mexico and spending the winter there. They’ll then move back to northern Mexico and Texas, where that generation breeds, lays eggs and dies. In the spring, the next generation hatches and heads back up north.

Hasle, who uses the pronoun they, said springtime conditions are very important for this migration, as monarchs rely heavily on environmental clues for timing. Changing climate patterns, such as changes to weather and freezing patterns in southern states, have a massive impact on these migrations.

“If you have a very small number and then they hit terrible spring conditions, then we’ll be really worried. We’re all praying for a wet, floral spring so that next generation can make it,” they said.

The International Union for Conservation of Nature considers monarch butterflies a vulnerable species. The group added the insects to its Red List of Threatened Species in 2022, classifying the insect as endangered, but dialed the classification back last year. Over the past 20 years, monarch populations have decreased by 85%, according to the Center for Biological Diversity.

Keeney said the decrease in monarch populations has implications for other pollinators. Other insects are also feeling the impacts of habitat loss, pesticide use and extreme weather.

A 2019 study published in the journal Biological Conservation found that 40% of insect species are threatened with extinction. Falling populations can impact food supplies, as pollinators like bees, wasps, flies and yes, butterflies are crucial for food production, she said.

Much of Keeney’s work centers around protecting prairie landscapes in Illinois, of which less than .01% is left. On the policy side, the environmental council advocates for pesticide and herbicide restrictions so they can still be used, but in a way that is “responsible for the ecosystem and the animals and plants that live in it,” Keeney said.

One of the best ways residents can support monarchs is by planting milkweed, the state wildflower. Milkweed is a main food source for the insects, and the only plant upon which they’ll lay eggs. Chicago residents can receive up to $60 toward locally bought, native plants, including milkweed, through the city’s Sustainable Backyards Program.

For those who don’t have the space to garden, volunteering and getting involved in other restoration projects is a great way to help, Hasle said. Building up monarch populations in the Midwest can reduce the impact of risk factors along their journey.

“This is an all hands on deck situation,” Hasle said. “We are building ecosystems that are more resilient to the changes that are coming with climate change. And that is what we can do.”

monarch butterfly among leaves
A butterfly sits on a leaf at Monarch Grove Sanctuary in Pacific Grove, Calif. Monarch populations dropped significantly this year compared to 2023. Nic Coury / Associated Press
monarch butterfly among leaves
A butterfly sits on a leaf at Monarch Grove Sanctuary in Pacific Grove, Calif. Monarch populations dropped significantly this year compared to 2023. Nic Coury / Associated Press

The monarch butterfly’s famed summertime visits to Chicago could be in jeopardy thanks to climate change and extreme weather.

Chicagoans may already see fewer of the graceful orange and black insects this summer.

Researchers in Mexico have observed a steep decline in the butterfly population ahead of its spring migration. Experts now worry those environmental factors could lead to the loss of the insect’s famed migration path altogether.

This winter marked the second-lowest number of migratory monarch butterflies since recordkeeping began in 1993. The pollinator completes the longest known insect migration each year, leaving northern climates in the United States and Canada for Mexico and California every winter. The monarch, the state insect of Illinois, already faces threats such as pesticide use and habitat loss that have contributed to their low migration numbers.

“The loss of the world’s longest migration path would certainly be an indescribable and devastating tragedy,” Lindsay Keeney, conservation director at the Illinois Environmental Council, said in an email. “As climate change accelerates, the species may adapt by shortening the migration path or even staying too long in southern climates where habitat is rapidly declining.”

The annual monarch butterfly count is calculated based on how many acres of land the insects cover when they land in forests west of Mexico City.

Mexico’s National Commission for Protected Natural Areas said the levels of migratory monarchs were 59% lower this January compared to last winter. The monarchs covered about 2.2 acres, compared to 5.4 acres in 2023. It’s the lowest count since 2013, which came in around 1.65 acres.

The significant one-year drop this winter makes experts worry. Aster Hasle, lead conservation ecologist at the Keller Science Action Center, a subsidiary of the Field Museum, said while it’s normal for insect populations to fluctuate year to year, this extreme of a drop is troubling. Abnormally hot, dry conditions this year — a result of climate change — were likely to blame.

Migratory monarchs typically start moving south in August, eventually reaching southern Mexico and spending the winter there. They’ll then move back to northern Mexico and Texas, where that generation breeds, lays eggs and dies. In the spring, the next generation hatches and heads back up north.

Hasle, who uses the pronoun they, said springtime conditions are very important for this migration, as monarchs rely heavily on environmental clues for timing. Changing climate patterns, such as changes to weather and freezing patterns in southern states, have a massive impact on these migrations.

“If you have a very small number and then they hit terrible spring conditions, then we’ll be really worried. We’re all praying for a wet, floral spring so that next generation can make it,” they said.

The International Union for Conservation of Nature considers monarch butterflies a vulnerable species. The group added the insects to its Red List of Threatened Species in 2022, classifying the insect as endangered, but dialed the classification back last year. Over the past 20 years, monarch populations have decreased by 85%, according to the Center for Biological Diversity.

Keeney said the decrease in monarch populations has implications for other pollinators. Other insects are also feeling the impacts of habitat loss, pesticide use and extreme weather.

A 2019 study published in the journal Biological Conservation found that 40% of insect species are threatened with extinction. Falling populations can impact food supplies, as pollinators like bees, wasps, flies and yes, butterflies are crucial for food production, she said.

Much of Keeney’s work centers around protecting prairie landscapes in Illinois, of which less than .01% is left. On the policy side, the environmental council advocates for pesticide and herbicide restrictions so they can still be used, but in a way that is “responsible for the ecosystem and the animals and plants that live in it,” Keeney said.

One of the best ways residents can support monarchs is by planting milkweed, the state wildflower. Milkweed is a main food source for the insects, and the only plant upon which they’ll lay eggs. Chicago residents can receive up to $60 toward locally bought, native plants, including milkweed, through the city’s Sustainable Backyards Program.

For those who don’t have the space to garden, volunteering and getting involved in other restoration projects is a great way to help, Hasle said. Building up monarch populations in the Midwest can reduce the impact of risk factors along their journey.

“This is an all hands on deck situation,” Hasle said. “We are building ecosystems that are more resilient to the changes that are coming with climate change. And that is what we can do.”