Diary of Monarch Migration

The "super-generation" of butterflies that migrates to Mexico each year is simply amazing. Learn about the monarch migration journey.

It’s an early summer morning, and an incredible new life is just beginning in the garden. It all started a few days ago, when a monarch butterfly laid an egg on a milkweed plant. The choice was no accident: Milkweed is the only food a monarch caterpillar can consume. And now this little caterpillar in Wooster, Ohio, has a job to do. Unlike other caterpillars that make a chrysalis, become butterflies and then die within a few short weeks, this one is part of the yearly “super generation.” Follow on butterfly as it joins in the annual monarch migration journey.

Monarch MigrationNellie Alexander
Soon, this caterpillar will be a butterfly and on its way to far-off Mexico.

Aug. 4 ~ Wooster, Ohio
The caterpillar is about the size of a pencil point. It stays on this plant, eating and growing nonstop, leaving only if it has finished every leaf and it must find new food. Caterpillars are very hungry indeed!

Aug. 17
About two weeks have passed since the egg hatched, and the caterpillar is about 2 inches long. It crawls away from the milkweed, finding a safe and sheltered place nearby, and goes to work creating a small silk pad. It attaches itself to the pad, hanging upside down to form a “J” shape. For 18 hours, the caterpillar is nearly motionless. Then the skin on its head suddenly splits to show a vivid green surface beneath. For several long minutes, the caterpillar wriggles, until at last the skin falls to the ground. Left behind is a soft green mass that hardens slowly into a waxy chrysalis. Now there’s nothing to do but wait.

Sept. 1
The chrysalis now shows patterns of orange and black. As the first rays of sun appear, the pod cracks open and the creature’s legs emerge. With effort, the rest of the body pushes out. Its crumpled wings soon straighten. The new butterfly, a female, hangs upside down, keeping still as her wings harden and dry. A couple of hours later, she flutters and flaps them, trying them out. Then the breeze catches her, and she’s off into the sky for her first flight.

Sept. 30 ~ Louisville, Kentucky
As part of the super generation, this monarch has no interest in mating just yet. Instead, instincts tell her to fly fast and far. She has already flown more than 300 miles from her birthplace, and her journey has barely begun.

Oct. 10 ~ Texarkana, Texas
The monarch is now flying almost 100 miles each day, often rising a mile into the sky where strong winds easily carry her. She joins with many others of her species going in the same direction, roosting at night in trees and nectaring from asters and other late wildflowers before starting out again. The days are growing short, and there’s no time to waste.

Oct. 17 ~ Ciudad Acuna, Mexico
Two months after leaving her birthplace, the monarch crosses into Mexico and joins millions of others to make clouds of orange in the blue sky. Her wings show wear and tear but beat faithfully, carrying her on without stopping. Soon enough, she’ll have plenty of time to rest.

Monarch MigrationLisa Comer
Lisa Comer Monarchs gather on the trees in such great numbers that branches sometimes break.

Nov. 2 ~ El Rosario winter colony, Michoacan, Mexico
Finally, she has reached the wintering grounds. It’s surprisingly cool here in the mountains, 10,000 feet above sea level. She settles with other monarchs into the oyamel fir trees, so thick with the creatures that branches sometimes crack from the weight. The insects’ bodies shut down, a type of hibernation known as torpor.

Dec. 30
Last night a terrible storm swept through the colony, with pounding rains, treacherous winds and freezing temperatures. This morning the ground beneath the trees is littered with the tattered bodies of butterflies that did not survive. Our monarch, however, is safe in her sheltered perch close to the tree trunk. She stirs briefly in the morning sun, then is still once more.

Feb. 23
Days are longer now, and the sun is stronger. High in the trees, the monarch begins to stir. Suddenly, she and others leave the trees, filling the air with a blur of orange and black. After months of near silence in the grove, the sound of flapping wings is unbelievably loud. The insects spread their wings in the warm sun and sip water from wet rocks. They won’t stay long, though; there is no food for them here, nor milkweed on which to lay eggs. They must start back north again, retracing their fall path.

March 15 ~ Abilene, Texas
Here in Texas, spring wildflowers are in bloom, and our female feeds on columbine while a male flutters nearby. After many months and thousands of miles, she is at last ready to mate. The two butterflies dance in the air and then join together. In a few days, she will begin to lay her hundreds of eggs on newly emerged milkweed plants. Her offspring and their offspring will complete the flight back to Ohio and beyond over several generations, each living only about six weeks. In the fall, another super generation will be born.

Monarch Migrationsshorten
sshorten The last task of the female’s life is to lay eggs on milkweed.

March 29 ~ Wichita Falls, Texas
She has laid all her eggs; it is her final task. Her wings are battered and ragged at the edges, faded and pale. Her body and wings are still, stirred only by a sweet spring breeze. The same gentle wind ruffles a milkweed leaf nearby, where a tiny caterpillar has just crawled from its egg. It raises its head to the sun, and the cycle begins anew.

Helping Struggling Monarchs
Sadly, monarch migration numbers are becoming smaller each year, as it has become harder for monarchs to find the right conditions to survive and make their incredible journey. Add these to your yard to help them out:

  • Milkweed. It’s absolutely vital to the survival of monarchs. There are more than 100 milkweed species; seek out those native to your area and plant as much as you can.
  • Nectar Flowers. Plants like asters, cosmos, zinnias and goldenrod provide the energy migrating butterflies need in late summer and fall.
  • Shelter. These intrepid fliers need safe havens for rest. Shrubs and ornamental grasses are ideal. Avoid so-called “butterfly houses,” which butterflies rarely use but which often attract wasps and other predators.

Jill Staake
Jill Staake's lifelong love of nature turned into a career during the years she spent working with native Florida butterflies, caterpillars, and other wildlife at the Museum of Science & Industry in Tampa, Florida. During this time, she helped to maintain 30+ acres of gardens and backwoods, all carefully cultivated to support the more than 20 species of butterflies displayed indoors and out. She now writes for a variety of publications and sites on topics like gardening and birding, among others.