The migrating Monarch butterfly, the North American subspecies, was declared endangered on July 21, 2022 by the International Union for the Conservation of Nature (IUCN).  This subspecies of the Monarch butterfly is known for its twice yearly 2,500 mile journey between its summer and winter areas.  

There are two North American populations; the western population (west of the Rockies) and the eastern population (east of the Rockies).  Although more is known about the eastern population, both have suffered dramatic declines in recent years; the western population has lost 99% of its members, declining from about 10 million individuals to about 250,000.  The eastern population has declined about 84% from 1996 to 2014.

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The major threats to Monarch butterflies are habitat destruction, especially in the wintering areas and pesticide use, primarily in the Midwest where glyphosate severely impacts the milkweed on which the Monarch depends. These threats are still of concern despite successful programs that have established monitoring and important way stations where milkweeds and other native plants have been established along the migratory route. 

The listing was announced because the threats to the Monarch populations are greater than current conservation efforts and it is hoped that by listing the Monarch as endangered it will stimulate additional conservation efforts.