Newsroom Midwest Region

The International Monarch Monitoring Blitz: A glimpse into the life of the monarch butterfly

Monarch caterpillar on common milkweed
A monarch caterpillar on common milkweed. Photo by Courtney Celley/USFWS.

We at the U.S. Fish and Wildlife Service know that citizen science is incredibly important to further our mission to conserve and protect species. The annual International Monarch Monitoring Blitz is an international citizen science effort to help tackle the challenge of conserving the beloved monarch butterfly. During this 10-day event, this year is from July 23 - August 1, 2021, thousands of volunteers in Canada, Mexico and the United States join together to observe monarchs and milkweeds. To participate in your nearest monarch blitz, simply search "monarch blitz" using any search engine and follow #MonarchBlitz on social media. These observations provide vital information on monarch habitat, migration patterns and population sizes. These snapshots into the monarch’s journey and milkweed abundances provide us with a better understanding of the dynamic relationship between the summer generations and their breeding habitat.

Monarchs and milkweed can be found all over North America, and that is why we need your help during this special event! The Blitz invites people across North American to look for milkweed plants and survey them for monarch eggs, caterpillars, chrysalises and butterflies. This data will help researchers identify priority conservation areas and actions. All information gathered during this annual event is uploaded to the Trinational Monarch Knowledge Network, where anyone may refer and download.

Monarchs are a truly special butterfly; they are the only butterfly species known to make a two-way migration. Monarchs travel as far as 3,000 miles to get to their overwintering habitat, which they do to avoid the freezing temperatures of winter. These overwintering sites were first recorded by scientists in California more than 200 years ago and in Mexico in 1975. Since then, the monarch has become a characteristic species of North America. During their journeys, they need plenty of flowers and milkweeds available, as monarch caterpillars feed exclusively on milkweed plants, and adult butterflies need a variety of nectar-bearing flowers throughout the year for food.

For the past four years, more than 2,000 volunteers have participated in the Blitz from Canada, Mexico and the United States. These volunteers documented more than 4,000 observations, with more than 123,000 milkweeds and 47,000 monarchs monitored. Due to these observations, we have noticed different population trends for the western and eastern monarch populations. After an alarming decrease in its populations over the last 20 years, the eastern monarch population overwintering in central Mexico showed a significant increase in 2018. However, the population suffered two consecutive drops in the past two years -53% in 2019 and 26% in 2020 compared to previous years-, remaining well below historic levels. Meanwhile, the western monarch population, which mainly overwinter along the California coast, is closer to extinction as only 1,914 monarchs were reported during the last Western Monarch Thanksgiving Count -a shocking 99.9% decline since the 1980s. Public participation in community science programs is more important than ever to help understand and reverse population declines and to continue to conserve the species.

By participating in the Blitz, you are contributing to a citizen science project that significantly benefits monarch conservation. Citizen science is especially important when other research methods have been disrupted due to COVID-19. However, the health and well-being of yourself and others come first. Before participating in any activities, know and carefully follow the health and safety measures for COVID-19 recommended by the authorities in your region. If you or a family member feel sick, stay home. Other ways you can help include creating monarch-friendly habitat on your property, reducing your use of pesticides and spreading awareness of the monarch’s journey to others.

A person takes a photo of a monarch butterfly
Taking a photo of a monarch butterfly. Photo by Lisa Hupp/USFWS.