A monarch butterfly clings to a plant at the Lurie Gardens at Millennium Park in Chicago on Sept. 7, 2021.
A monarch butterfly is seen in Debbie Kostolansky’s butterfly garden in Orland Park in 2021. One of her tagged monarchs was seen in Mexico the previous year.
A monarch butterfly rests in a clear plastic container before being released by Samantha Goodman and her 6-year-old son, Torben Goodman, outside their home on Sept. 1, 2021, in Chicago.
A monarch butterfly flutters at Lurie Gardens at Millennium Park in 2021.
Milkweed, which is vital to the survival of monarch butterflies, is one the native plants found near the Shedd Aquarium in Chicago on Sept. 7, 2021.
A monarch butterfly takes flight at Lurie Gardens at Millennium Park in Chicago, Sept. 7, 2021.
A monarch butterfly visits perennials at Lurie Gardens at Millennium Park in Chicago, Sept. 7, 2021.
A monarch butterfly spreads its wings on Sept. 5, 2019, at Lurie Garden in Millennium Park.
Monarch butterflies rest on giant hyssop perennials Aug. 30, 2019, in Lurie Garden at Millennium Park in Chicago.
A monarch butterfly sits on a coneflower July 26, 2019, at Millennium Park.
Monarch butterflies cluster on giant hyssop perennials Aug. 30, 2019, in Lurie Garden at Millennium Park.
An egg laid by a monarch butterfly is attached to a milkweed leaf in the backyard of Karen Hallman’s home on Chicago’s Northwest Side on June 13, 2019.
Simon Tolzmann, 14, holds a dead monarch butterfly near Foster Beach on Oct. 7, 2019, in Chicago.
A monarch butterfly sits on a coneflower at Millennium Park on July 26, 2019.
Eleri Williams, 8, watches a monarch caterpillar pupate into a chrysalis at her home in Chicago’s Uptown neighborhood July 3, 2019.
The wings of a monarch butterfly begin to show through its chrysalis.
An emerged monarch butterfly unfolds its wings in Lisa Meehan’s home on July 3, 2019.
A monarch chrysalis in Karen Hallman’s backyard on Chicago’s Northwest Side on June 13, 2019.
A monarch caterpillar appears on a milkweed leaf.
A monarch butterfly perches atop a purple coneflower in Millennium Park’s Lurie Garden on July 12, 2018.
Kay MacNeil holds one of several monarch caterpillars in her Frankfort home on Aug. 25, 2016.
Swarms of monarch butterflies alight Sept. 7, 2018, in the Lurie Garden at Millennium Park.
A monarch butterfly settles on a plant July 26, 2018, at Jesse White Park and Community Center.
A monarch butterfly visits flowers Sept. 24, 2015, at Gompers Park in Chicago.
Swamp milkweed grows at a home in Lombard on June 18, 2015. Monarch butterfly caterpillars need milkweed to survive.
