The annual Monarch Butterfly migration has begun. The monarchs west of the Rocky Mountains will travel to small groves of trees along the California coast. The monarchs east of the Rocky Mountains will fly high to the Sierra Madre mountains of Central Mexico. It’s a 2,000-3,000 mile journey for these insects.

 

 

The forests where the monarchs overwinter are at 8,000 to 12,000 feet and are hidden in cloud cover, providing the ideal temperature and humidity for them to survive. Amazingly, they fly to the same winter roosts -- sometimes to the exact same trees.

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The monarchs begin their northward migration in early March. Monarchs will undergo three to four generations before they return to the Midwest, each generation dying off shortly after reproducing.

The monarch population has been in decline for the past 20 years as milkweed plants are destroyed from rural areas. The only thing that monarch caterpillars eat is the leaves of the milkweed plants.

The butterflies, while not yet officially recognized as an endangered or threatened species, meet the criteria for inclusion, according to the U.S. Fish and Wildlife Service.

Over the past couple of decades, scientists have estimated that the eastern population of Monarch butterflies fell from about 384 million in 1996 to a low of 14 million in 2013. The population in 2019 was about 60 million. The western population, located in California, saw a more precipitous decline, from about 1.2 million in 1997 to fewer than 30,000 in 2019.

One way to track monarch butterflies is by tagging their wings. Last fall, a monarch butterfly that was tagged in Dallas County, Iowa made its destination to Mexico.

According to the Iowa DNR, it took this butterfly 39 days and some-1,800 miles to reach its destination.

During the summer breeding season, monarchs live for only 2-6 weeks. But the monarchs that migrate to Mexico in the fall are different: They are born in late summer, stay alive all winter, and then migrate north in the spring.

How can you help the Monarch? Plant milkweed and don’t use pesticides on your property.

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