What's New With Those Monarch Butterflies & Their Migrations?

It's been reported that both Eastern and Western monarch butterfly populations are declining. Researchers this year are unsure if these majestic butterflies are making it to breeding sites, finding mates, or are starving in transit. According to a New York Times report, the population of Western monarchs was in the millions in the 1980s, down to 200,000 three years ago, and then plummeting to only 30,000 in 2018.

Various Factors

There are various factors affecting the demise of these insects. Matt Forister, an ecologist at the University of Nevada, Reno, said that research identified various factors in butterfly loss, including development, climate change, farming practices and widespread pesticide use by farmers and on lawns.

East Coast

On the East coast, there are fewer Eastern monarch butterflies migrating this summer. According to a new population survey, the Eastern monarch has passed the extinction threshold, according to a new population survey by the Center for Biological Diversity.


The monarch caterpillars diet is based solely on milkweed. However, this plant has been diminished by increased herbicide spraying in conjunction with corn and soybean crops that have been genetically engineered to tolerate direct spraying with herbicides. Today, monarchs are threatened by most herbicides and by neonicotinoid insecticides that are toxic to young caterpillars and have decreased the health of adult butterflies.

Plants like milkweed in the United States and Canada are essential for monarch reproduction; it's the only plant where monarchs lay their eggs and where baby larvae feed on.

Endangered Species Act

“Both the law and science require that we must protect monarchs under the Endangered Species Act before it’s too late,” said George Kimbrell, legal director for the Center for Food Safety.

Migration modifications

The Western monarch, which is slightly smaller and darker than the Eastern monarch, has a more concentrated migratory pattern. While the Eastern monarch travels from Mexico all the way to New England and Canada, the Western monarch tends to only go south as far as California, traveling as far north as British Columbia and east as far as the Rockies. But in recent years, it has narrowed its path and does not make it as far as Washington.

Actions to revitalize Monarch populations

The World Wild Fund [WWF] works with the Mexican government, local communities, and partners to protect the monarch hibernation grounds in the Monarch Butterfly Biosphere Reserve. They also support sustainable projects that provide an economic alternative to the people who live in the monarch region.

1 Million For Monarchs

The WWF has set a goal of signing up 1 million supporters to come together under the title of the  'Monarch Squad.' Those who join will receive the following:

  • Get the latest news and information about migrating monarchs
  • Learn how, where, and when to grow the plants that monarchs need to survive
  • Be the first line of defense and provide a voice for monarchs on important policy decisions

If interested, you can join here.


Primary Source: NY Times