These butterflies, which inhabit and breed on over a billion acres across North America throughout the year, all end up in a tiny 10-acre area in central Mexico. It’s hard to fathom.
Monarch Butterflies are truly a phenomenal species that bewilders scientists who try to figure out the annual migration monarchs make from the Oyamel fir forests in central Mexico to Canada and back. This journey is shared by four to five generations. Yet somehow, Monarchs are imprinted to end the migration in the same tiny area where their ancestor began. These butterflies, which inhabit and breed on over a billion acres across North America throughout the year, all end up in a tiny 10-acre area in central Mexico. It’s hard to fathom.
Monarchs that overwinter in Mexico head to Texas in early spring to lay eggs and die. Those eggs hatch and that generation migrates north to the Missouri area to lay eggs and die. The next generation makes it to northern Iowa or southern Minnesota, and the next into Canada, each with the goal of reproducing before perishing. These northbound Monarchs live four to five weeks. But the next generation, the Methuselahs, they leave out of Canada in the fall and fly all the way back to Mexico, often returning to the same exact tree their great-great grandparent left from in the spring. The Methuselahs overwinter in Mexico and head to Texas in the spring. They live up to eight or nine months.
Kelly Srigley-Werner is the Missouri Partners for Fish and Wildlife Program State Coordinator for the U.S. Fish and Wildlife Service working out of the Columbia, Missouri office. She said, “The monarch butterfly in the past two decades has had a population collapse. There were close to a billion Monarch butterflies 20 years ago wintering on about 45 acres. In the winter of 2013-2014 the population had declined to an estimated 33 million, occupying just 1.66 acres. The problems that are happening revolve around habitat loss and climatic issues affecting Monarch wintering grounds in Mexico.”
Monarchs undergo complete metamorphosis. Like all moths and butterflies, they have four parts to their life cycle: egg, caterpillar, pupa, and adult. The process takes about a month to complete. All moth and butterfly species rely on a host plant that is chemically compatible with their species. For monarchs, only milkweeds can serve as a host.
“Milkweed is essential to Monarch butterflies, because they are the only plants females lay their eggs on and the only plants the caterpillars eat before becoming butterflies. There are a number of milkweed species in Missouri. The ones most prevalently used by monarchs are Swamp Milkweed, Common Milkweed, Butterflyweed, Purple Milkweed and Whorled Milkweed,” Srigley-Werner said.
Once a female monarch mates with a male, she must find a milkweed to lays her eggs. Caterpillars hatch usually within in a week. These caterpillars molt five times, shedding their skin and growing slightly larger each time. After the fifth molt, the caterpillar forms a chrysalis, in which it turns into a butterfly. The butterfly, weighing about as much as two soybeans, forces itself out of the chrysalis and begins its leg of the journey.
Native nectar sources are of great importance because adult monarchs require nectar to live. Native Missouri nectar plants monarchs prefer include Eastern Blazing Star, Purple Coneflower, Showy Goldenrod, Smooth Astor, Wild Bergamot and more. Unfortunately, we continue to see a decline in native wildflowers, along with milkweeds. Habitat change is the greatest factor in the decline of the monarchs and all other pollinators.
Monarchs are vital to agriculture. Pollinators move pollen from one flower to another. They actually fertilize the plants, allowing for reproduction. More than 30 percent of our food relies on pollinators. Fruits, like strawberries, cherries, apples, tomatoes and melons wouldn’t exist without pollinator insects.
“The U.S. Fish and Wildlife Service is working with Canada and Mexico on an international scale to coordinate and collaborate on Monarch habitat, But we are also working close to home. We are working with the National Fish and Wildlife Foundation for additional funding so people can compete for grants to get funds to help with habitat restoration. We are working with communities, federal and state agencies, non-government organizations, individuals; it’s all hands on deck for the monarch,” Srigley-Werner said.
Missouri is located in the heart of the annual monarch butterfly migration. Making our state is a key geography to monarch restoration efforts. A lot of the population is found along the I-35 corridor, but don’t think of that as a narrow window because it’s actually around 400 miles wide. Monarchs must find milkweed and nectar sources in the corridor to survive. These days they’re having a much harder time doing so.
Monarchs begin appearing across Missouri towards the end of April. They show up in southern Missouri first and work their way north. So if you see a monarch in the spring, it’s heading north. Starting in August and through much of September, we’ll start seeing monarchs again heading south to Mexico.
See you down the trail…