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Monarch Butterflies

To ensure healthy ecosystems, the Xerces Society’s endangered species team conserves at-risk species and their habitats through research, advocacy, education, conservation planning, and restoration. Our team of conservation biologists holds degrees in entomology, ecology, biology, and environmental science, and has decades of experience working with rare and at-risk terrestrial and aquatic invertebrates. We share a passion for conserving invertebrates that are imperiled with extinction.

Our roads and highways present unique opportunities for creating corridors to support monarchs and other pollinators. In some areas, roadsides may be the only places where milkweed and nectar plants may be available. When managed with pollinators in mind, roadsides have the potential to add miles and miles of high-quality habitat while reducing maintenance costs. Learn more about how roadsides can be managed to reduce costs and protect pollinators.

To conserve monarchs and their habitat Xerces works with farmers and farm agency staff to install high-quality habitat for pollinators, enhance and manage existing habitat, and protect habitat from pesticide exposure. We have partner biologists and conservation planners across the eastern US who are working with farmers and ranchers to provide technical assistance on restoration, enhancement, and management projects for pollinators – including monarchs.
Many of our natural areas – including wildlife refuges, rangelands, national forests and grasslands, rights of ways, as well as parks and other open spaces in towns and cities provide habitat for monarch butterflies to eat, lay eggs, and take shelter. The Xerces Society has developed a variety of tools for managers of natural areas to facilitate managing and enhancing habitat for monarch butterflies.
Monarch butterflies east of the Rocky Mountains used to number in the hundreds of millions but the population has declined by over 80%. Loss of habitat due to genetically modified crops, overuse of insecticides, and urban, suburban and agricultural development, are the leading causes of monarch decline. The Xerces Society is working with farmers, ranchers, park and natural areas managers and gardeners across the eastern US to plant milkweed and nectar plants needed for monarch’s survival.
While the Xerces Society engages in monarch conservation efforts across North America, partnering with leaders in the U.S., Mexico, and Canada - a significant amount of our work focuses on monarch populations in western states, where overwintering populations have declined by 97% since the 1980s.

An epic migration, on the verge of collapse.  

In the 1990s, nearly 700 million monarchs made the epic flight each fall from the northern plains of the U.S. and Canada to sites in the oyamel fir forests north of Mexico City, and more than one million monarchs overwintered in forested groves on the California Coast.

Milkweeds (Asclepias spp.) are the required host plants for caterpillars of the monarch butterfly and thus play a critical role in the monarch’s life cycle. The loss of milkweed plants in the monarch’s spring and summer breeding areas across the United States is believed to be a significant factor contributing to the reduced number of monarchs recorded in overwintering sites in California and Mexico.

Monarchs are in decline across their range in North America. Loss of milkweed host plants due to extensive herbicide use has been identified as a major contributing factor, and loss or degradation of nectar-rich habitat from other causes, natural disease and predation, climate change, and widespread insecticide use are probably also contributing to declines.