Monarch migration numbers decline as milkweed disappears from the landscape

September may signal the end of summer for most of us, but it is the beginning of a huge adventure for one delicate species.

The monarch butterfly migration occurs in the early weeks of September and spans from Canada to Mexico or southern California where the butterfly will overwinter. The monarchs seen heading south are not the same butterflies that came north earlier in the year. It takes three to four generations to reach the northern U.S. and Canada, according to the USDA. It is the fourth generation of monarchs that travel up to 2,500 miles to escape the harsh conditions of the winters in the Midwest.

“That’s what’s so amazing … that these insects make such a long trip having never been there before,” said Bruce Barrett, MU professor of Plant Sciences.

The milkweed plant is one of the most vital resources in the life of monarchs. Often found roadside and in many crop fields, these plants are the only place female monarchs lay their larva and the only food source their caterpillars consume. Monarch caterpillars depend on the plant not only for food, but also for the organic compound cardiac glycosides that makes the insect toxic to its predators.

According to the National Geographic, there has been a 21 percent decline in the plant’s development from 1995 to 2013.

“We put a value of worth only when we see worth,” Barrett said. “Monarchs are important not because they are pretty, but because they are a part of our ecosystem.”

These butterflies, which for centuries have been a signal of environmental health, are now in need of help to ensure the development of their future generations. Many educational, scientific, and conservation professionals alike see the recent decrease in the population of such a symbolic creature as a clarion call that it is time for a change.

“It’s as simple as planting a milkweed on the outer edges of our lawns …. Just planting one can help save a million,” said Barbara Sonderman, MU biological science greenhouse coordinator.

Since the initial reports of the monarch population decline, many conservation programs have been developed to help reverse the trend. For more information on native milkweeds, and information to help save the monarch visit: