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Goldenrod provides migrating monarchs with a vital food source.
Monarch Butterfly Goldenrod provides migrating monarchs with a vital food source. © Shutterstock

Animals We Protect

Monarch Butterfly

Danaus Plexippus

Monarch butterfly River Fork Ranch
Monarch butterfly River Fork Ranch Monarch butterfly at River Fork Ranch Preserve in the Carson Valley, NV. © Simon Williams/The Nature Conservancy

Monarch Butterfly Fast Facts

Common name: Monarch butterfly

Scientific name: Danaus plexippus

Conservation status: Apparently secure

Lifespan: 2 to 6 weeks

Wingspan: 3.5-4 inches

Meet the Monarch Butterfly

The monarch butterfly is one of the most easily recognized butterflies, distinctive with its black and orange wings. The color pattern is recognized by potential predators as well, signaling that the insect may contain poison from the milkweed on which it feeds as a caterpillar.

The monarch is native to the Americas but has colonized such far-flung locales as Western Europe and Australia. Traditionally two main populations have been recognized: one east of the Rocky Mountains and one west. The eastern population migrates south to central Mexico, the western to California. Recently scientists have suggested that the two populations commingle extensively.

The monarch undertakes annual generational migrations:

  • In central Mexico, tens of millions of butterflies overwinter in less than 20 sites, gathering in 20-30 million per large roost.
  • They begin to disperse in late February and early March, mating and then flying north, usually making it to Texas before laying their eggs on milkweed plants.
  • The next generation continues the migration, leapfrogging north until the third or fourth generation arrives as far north as Canada in May and June.
  • This final generation migrates up to 2,200 miles back to Mexico, arriving in early November. They begin migrating singly and then are slowly funneled into flocks as they converge on roosting sites.

As they fly south, the butterflies may fly as high as 4,000 feet while riding thermals, averaging a stately 12 miles per hour. Intermediary generations have an adult lifespan of only 4-5 weeks, but the final annual generation lives 5-7 times longer, making the long migration and then surviving to overwinter, mate and return north.

A monarch  butterfly visits a flower in Kentucky.
Monarch Butterfly A monarch butterfly visits a flower in Kentucky. © Chris Helzer/The Nature Conservancy

The monarch undertakes annual generational migrations:

  • In central Mexico, tens of millions of butterflies overwinter in less than 20 sites, gathering in 20-30 million per large roost.
  • They begin to disperse in late February and early March, mating and then flying north, usually making it to Texas before laying their eggs on milkweed plants.
  • The next generation continues the migration, leapfrogging north until the third or fourth generation arrives as far north as Canada in May and June.
  • This final generation migrates up to 2,200 miles back to Mexico, arriving in early November. They begin migrating singly and then are slowly funneled into flocks as they converge on roosting sites.

As they fly south, the butterflies may fly as high as 4,000 feet while riding thermals, averaging a stately 12 miles per hour. Intermediary generations have an adult lifespan of only 4-5 weeks, but the final annual generation lives 5-7 times longer, making the long migration and then surviving to overwinter, mate and return north.

 Monarch butterfly eggs
Monarch butterfly eggs These eggs are typically planted on the underside of a milkwood plant and take 3 to 8 days to develop and hatch into caterpillars. © Kevin Arnold
Monarch caterpillar
Monarch caterpillar After the eggs hatch, a caterpillar emerges. These caterpillars go through five stages before they enter the chrysalis stage where they transform into an adult butterfly. © Chris Helzer/TNC
Monarch butterfly eggs These eggs are typically planted on the underside of a milkwood plant and take 3 to 8 days to develop and hatch into caterpillars. © Kevin Arnold
Monarch caterpillar After the eggs hatch, a caterpillar emerges. These caterpillars go through five stages before they enter the chrysalis stage where they transform into an adult butterfly. © Chris Helzer/TNC
Progression of the monarch from caterpillar to chrysalis to butterfly.
Monarch Lifecycle Progression of the monarch from caterpillar to chrysalis to butterfly. © Full Sail University

Protecting the Monarch Butterfly

Researchers estimate that a jaw-dropping 970 million monarchs have vanished since 1990.

There are a number of threats to monarch butterflies including habitat loss, climate change and agricultural pesticide use that is reducing milkweed populations—a plant on which the monarch lays its eggs.

There are only eleven to fourteen mountaintops in Mexico where these butterflies can find a safe haven to wait out the harsh winters in temperate climates. These areas are being targeted for new roads, housing developments and agriculture expansion. In the southern coastline of California, the stands of eucalyptus trees, Monterey pines and Monterey cypresses are in danger of being cut down due to the rate of land development in the surrounding area.

TNC is encouraging citizen scientists in a number of U.S. states to help track monarchs. This data will help researchers understand if monarch migration patterns are changing due to climate change or habitat loss. The Conservancy’s land stewards are also helping monarch populations by planting local and native species of milkweed at many preserves across North America.