On Thursday, scientists put the monarch butterfly on the endangered list as its population has declined between 22% to 72% in the past 10 years.
The butterflies are imperiled by the loss of habitat, increased use of pesticides and herbicides, and climate change, according to Emma Pelton of the nonprofit Xerces Society.
The International Union for the Conservation of Nature categorized the iconic orange-and-black butterfly as "endangered," two steps from extinct.
The United States has not classified monarch butterflies under the Endangered Species Act, but several environmental groups think it should.
In North America, millions of monarch butterflies undertake the longest migration of any insect species, between Mexico and Canada.
In Central and South America, non-migratory monarch butterflies are not designated as endangered.
