Migratory Monarch Butterflies Are Now Endangered

Iconic monarch butterflies are officially at risk of extinction.

Migratory monarchs (Danaus plexippus plexippus) have been classified as endangered by the International Union for the Conservation of Nature (IUCN). They’re now just two steps away from being labeled as extinct on the group’s Red List of threatened species.

The IUCN says the well-known orange and black insects face threats from habitat destruction and climate change.

The migratory monarch is a subspecies of the monarch butterfly (Danaus plexippus). The insects are known for their impressive migrations, traveling as much as 3,000 miles from the cool north to the warmer south to spend the winter.

After spending the winter in Mexico, they migrate back north. It takes at least four generations of monarchs to make the trip back to southern Canada before returning back at the end of summer. Millions of butterflies make the trek.

The IUCN estimates that over the past decade, the breeding ground in the U.S. and Canada for monarchs has diminished between 22% and 72%. Much of their habitat has been destroyed by logging and deforestation for urban development and farming. In addition, the use of pesticides and herbicides across their range kills both the butterflies and milkweed, the plant that butterfly larvae depend on to survive.

Climate change has also played a part. Drought and wildfires affect milkweed growth. Extreme temperatures cause butterflies to begin migrations before enough milkweed is available. And severe weather has also killed millions of the insects, according to the IUCN.

“It is difficult to watch monarch butterflies and their extraordinary migration teeter on the edge of collapse, but there are signs of hope,” Anna Walker, member of the IUCN SSC Butterfly and Moth Specialist Group and species survival officer at the New Mexico BioPark Society, said in a statement. Walker led the monarch butterfly assessment for the IUCN.

“So many people and organizations have come together to try and protect this butterfly and its habitats. From planting native milkweed and reducing pesticide use to supporting the protection of overwintering sites and contributing to community science, we all have a role to play in making sure this iconic insect makes a full recovery.” 

Steps Toward Conservation

Although it’s bad news that a species moves closer to being labeled as extinct, the classification gives conservationists some tools to help protect them.

"The decision by IUCN to add migrating monarch butterflies to their 'red list' of endangered species is an important step forward in protecting this iconic butterfly species," said Mark Hunter, professor of ecology and evolution biology at the University of Michigan.

Hunter focuses on how insects and plants react to changes in the environment and has been studying monarchs and milkweeds for more than 20 years.

“At the University of Michigan Biological Station, we have measured precipitous declines in monarch populations over the past couple of decades. Like many migratory species, monarchs are exposed to multiple environmental threats as they make their journey between the United States and Mexico,” Hunter says.

"Because monarchs are so well studied, they can serve as a 'canary in the coal mine' for other endangered species. For example, fully 50% of the other insect species that eat milkweeds have also declined in northern Michigan. We need sustained conservation efforts if we are to protect monarch butterflies and the other insects with which they live."