Monarchs on milkweed. (ISU photo)

Researchers at Iowa State University say the continent’s monarch populations appear to be shrinking, despite vigilant efforts in Iowa and elsewhere to help the fragile butterflies recover their numbers.

Steve Bradbury, an ISU entomology professor, says the survey released last month of overwintering monarchs in Mexican forests dropped about two acres from a year ago.

“It was at about five acres of occupied forest canopy and our long-term goal is 15 acres,” Bradbury says. “People were hoping they were going to go up but weather conditions during different parts of the migration, especially the spring migration, knocked the numbers down in the U.S. and that sort of cascades.”

The loss of habitat in the U.S. and forest degradation in Mexico is also contributing to the population’s decline. He urges Iowans to step up their efforts to save this key pollinator.

“I think we’re having a positive impact with all of the work people are doing to get the voluntary programs moving forward,” Bradbury says. “I think the challenge is, it just takes time, and patience is really important.”

Planting milkweeds and flowers is only part of the task. A 20-year plan is in place that supports habitat improvements in rural landscapes that don’t conflict with agricultural production to bring about improved monarch breeding success and to complement other conservation programs.

“The milkweed plants themselves, which the larvae need for their diet and that’s the only plant the females lay their eggs on,” he says, “but also, blooming wildflowers are really important for the adult monarchs to get resources, food, when they’re up here laying eggs as well as for the generation that goes down to Texas and into Mexico.”

Bradbury urges Iowans to learn online about how vital pollinators are to Iowa’s ag industry and how dozens of groups are working to save them through the Iowa Monarch Conservation Consortium.

“On that website, we have a lot of information about how to establish habitat from agricultural settings to urban and suburban settings,” Bradbury says. “It’s an all-hands-on-deck effort and our website has lots of helpful information.”

The U.S. Fish & Wildlife Service is considering adding the butterfly to the list of threatened and endangered species. The monarch becomes a candidate for listing in 2024.