The International Union for the Conservation of Nature added the migrating monarch butterfly for the first time to its “red list” of threatened species and categorized it as “endangered.” That puts it two steps away from "extinct." The United States has not listed monarch butterflies under the Endangered Species Act, but several environmental groups believe they should be listed. (Nonmigratory monarch butterflies in Central and South America were not designated as endangered.)
The population of monarch butterflies in North America is estimated to have declined between 22% and 72% over 10 years, depending on the measurement method. Nick Haddad, a conservation biologist at Michigan State University estimates that the population of monarch butterflies he studies in the eastern United States has declined between 85% and 95% since the 1990s.
In North America, millions of monarch butterflies undertake the longest migration of any insect species known to science. They winter in the mountains of central Mexico and then migrate north. They breed multiple generations along the way for thousands of miles stretching through New Jersey and as far north as southern Canada.
They begin the trip back to Mexico at the end of summer.
Butterflies generally are dropping their numbers because of loss of habitat, increased use of herbicides and pesticides for agriculture, and climate change.
Many Americans have been trying to do their part by planting butterfly gardens or adding plants such as milkweed, a plant that the caterpillars depend upon.
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