ST. LOUIS — A proposal is underway by the U.S. Fish and Wildlife Service to list monarch butterflies under the Endangered Species Act as threatened.

Sightings of the popular insect across Missouri and the country were rare this fall as they migrated south to Mexico for the winter.

Scientists measure the population of monarchs in acres of space they take up when they land in Mexico. Last year was the second smallest number of monarchs recorded in over 30 years — a 59 percent decrease, according to the Butterfly House in Chesterfield.

“The declining monarch population recorded last winter raised the alarm for many scientists, and we still believe there is cause for concern and a need to educate the public on this topic,” said Tad Yankoski, senior entomologist at the Butterfly House.

"If the population continues to decrease at the current rates, the monarch migration as we know it could soon cease to exist. We will continue stressing the importance of supporting natural habitats and creating waystations for monarchs in Missouri and the surrounding area.” 

Each year, monarchs travel from southern Canada to central Mexico and back. It may take four generations for monarchs to make it from Mexico to Canada and a single generation to fly back.

Throughout their journey across North America, monarchs are exposed to climate change and pesticides that result in loss of habitat and food.

If the proposal to list monarchs under the Endangered Species Act is approved, it would allow species-specific protections of the flying insect.

The public has an opportunity to submit comments for the proposal through mid-March.

The comments will be evaluated by the U.S. Fish and Wildlife Service that will help determine the monarchs' status.

Public informational meetings will be held Jan. 14 and Jan. 15. Those interested can register online for the meetings.

To help save the monarchs, people can plant native milkweed and other pollinator plants, use less pesticides and encourage habitat preservation.