CHICAGO — Monarch populations have plummeted — but Chicagoans can help boost their numbers when the butterflies flutter through the city this year.
Ecologists and other scientists have been warning about an 80 percent decline in monarch populations due to habitat loss, pesticides and climate change over the past two decades, but 2024 is a critical year. A recently released annual survey on monarch populations reported a 59.3 percent decrease in population from 2022, the lowest since 2012-2013. Abigail Derby Lewis, senior conservation ecologist at the Field Museum, called the results “bleak.”
The survey found monarchs occupied 0.9 hectares of forest in Mexico in late December, with one hectare containing 20-30 million monarchs. That’s a stark difference from 1996-1997, when the survey found butterflies occupying 18.19 hectares of land.
While there can be natural increases and decreases of populations over the years, it’s much harder for the population to bounce back when you have such a low starting point like this year, Derby Lewis said.
But Chicago is an important summer breeding area for migrating monarchs — which means neighbors can help get their numbers back up.
“It’s kind of our job here in the Midwest to build that population back as large as possible over the summer,” Derby Lewis said.
The best way to do that is planting milkweed, the only plant that monarchs lay eggs on and that the caterpillars will eat.
Here’s everything you need to know to help save the monarchs.
What Type Of Milkweed To Plant
Common milkweed (Asclepias syriaca) can grow pretty much anywhere. It’s a favorite of monarchs, according to Monarch Watch.
There are other species you can put in your garden, though. Liz Vogel of North Branch Natives, a gardening company that specializes in native plants, recommended planting one of three: butterfly milkweed (Asclepias tuberosa), whorled milkweed (Asclepias verticillata) and Sullivant’s milkweed (Asclepias sullivantii).
Although common milkweed has a reputation for spreading and taking over gardens, these other milkweed species are not as aggressive, Vogel said.
The Field Museum has a guide to creating a monarch garden, and it includes information about milkweed species and nectar-producing plants you can grow locally.
How To Plant Milkweed
Many plant centers sell milkweed seeds, and it is typically more affordable to grow plants from seed.
Milkweed seeds require a period of freezing and thawing, mimicking the end of winter. Vogel said that process can happen naturally with the ups and downs of temperatures in March if Chicagoans plant seeds outside now.
You can also mimic that cycle by wrapping seeds in a damp paper towel and putting them in your refrigerator for eight to 12 weeks before planting them outside, said Kayri Havens, chief scientist and Negaunee vice president of science at the Chicago Botanic Garden.
Milkweed is fairly versatile and can be planted in large pots or directly in the ground.
For planting in a pot, find a container, put the seeds on top and sprinkle soil over them, Vogel said. Water well and put the pot in a protected place so that excessive water from rain, snow or wind won’t disturb the seeds.
For planting in the ground, Vogel recommended first clearing the area of organic matter and loosening the soil with a rake. Then sprinkle the seeds and put them into the soil. The remaining organic debris can be helpful to block the wind until the seeds take root.
Generally, milkweeds prefer full sun or partial shade.
When Will You See Monarchs In Chicago?
Monarch butterflies can be spotted as early as April, when the migrating butterflies typically start to reach Illinois, according to the Illinois Department of Natural Resources. They’ll lay eggs that will grow up and live in Chicago throughout the spring and summer, with some monarchs spotted in the fall before the last brood migrates to Mexico.
In the past, the Museum Campus has been a prime viewing spot for seeing monarchs in the fall.
Other Ways To Help Monarch Butterflies
Other Plants
While monarchs must have milkweed to reproduce, you might consider planting other flowers to provide nectar to grown monarchs and other pollinators throughout the season, Havens said.
“Not only is it beautiful, but it’s also beneficial to the insects and birds and other critters that use your garden as habitat,” Havens said.
Vogel said plants tend to do better with buddies, recommending combinations like butterfly milkweed, prairie dropseed and purple prairie clover — plants native to the area.
Other combinations include whorled milkweed, sideoats grama and black-eyed Susan.
Don’t Use Pesticides
Pesticides can harm monarch butterflies and other pollinators, so you should avoid using them, according to the Illinois Department of Natural Resources.
Budburst
The Chicago Botanic Garden has a community science project you can participate in called Budburst. The project asks locals to observe monarchs to gather information about whether the butterflies prefer laying eggs on flowering and non-flowering milkweed plants, Havens said.
Click here for more information about the project.
Support Local News!
Subscribe to Block Club Chicago, an independent, 501(c)(3), journalist-run newsroom. Every dime we make funds reporting from Chicago’s neighborhoods. Already subscribe? Click here to gift a subscription, or you can support Block Club with a tax-deductible donation.
Listen to the Block Club Chicago podcast:
