The Magnificent and Mysterious Monarch Migration

Monarch butterfly prepares for flight. Photo by ASWang
Monarch butterfly prepares for flight. Photo by ASWang

The moment I laid eyes on a chunky yellow, black and white-striped monarch caterpillar (larva), I was hooked. It is colorful, peaceful and eats a lot. It’s mesmerizing to observe.

But all this munching is in preparation for something profound, a phenomenon known as the monarch butterfly migration, a fierce journey of up to 3,000 miles in about 2 months from this majestic pollinator that faces multiple perils.

After 12 days or so of emerging from its egg and 5 instars later (shedding old skin and emerging into a larger caterpillar each time), it pupates, turning into a lovely light green jewel of a chrysalis speckled with a shimmering gold crown and a matching golden arc pattern beneath, like a priceless pendant worthy of royalty.

Finally, after being motionless for 10-14 days, the chrysalis turns black, then translucent and the great transformation that took place inside is revealed.

A glorious orange and black butterfly emerges, about 4 inches wide. It takes within 10 minutes to 2 hours to unravel its wings, pumping fluid into and flapping them while they dry and prepare for flight.

But even more than being beautiful and graceful, the delicate monarch butterfly is relentless in its keen sense of travel and highly adaptable under pressure.

“They are incredibly robust in their survival strategies… They’re pretty hardy! To fly as far as they do, they have to be!” says Gail Morris, conservation specialist in Arizona.

Among all insects, it stands alone in its determination to survive by an ability deeply rooted in its DNA to migrate to overwintering sites in the oyamel forests of Mexico, the tip of Florida and the coast of California.

But this unique migration is in danger of extinction. Generally speaking, there are two populations of monarchs within the same species, one to the east and one to the west of the Rocky Mountains. And each has its own migration pattern.

The traditional thinking has been that these two populations are completely separate. But recent studies from the Southwest Monarch Study and partners who tagged monarchs in the West, found that some made their way further south, overwintering in Mexico with the predominant eastern population of fall migrators.

According to Dr. Robert Pyle, founder of the Xerces Society and author of Chasing Monarchs, “The Continental Divide is not the absolute dividing line between Mexican and Californian migrants, as has always been said. Basically, the westernmost (coastal, S Oregon, Northwest) monarchs migrate to the California coast, while some of the inland ones migrate to Mexico. We have no idea how many or what determines the destination.”

The monarch migration in the East is better understood and documented than the western migration pattern that is still being discovered.

The monarchs in the East begin their spring migration to the North in the oyamel forest, when the sun warms their bodies and conditions are suitable for travel. It takes about a month to land in the southern parts of the United States, east of the Rockies. The females lay nearly 400 eggs on multiple milkweed plants to ensure the survival of at least 3 into adulthood! The parent monarch, the first generation, then dies.

The spring migration is brutal. The bright colors on the larva and the orange on the butterfly is a warning that they are poisonous, but this does not deter some predators. And not only do the monarchs face wind conditions that often flow against the direction they’re headed, but also the cost of reproduction is a toll on their longevity.

The second generation takes another 4-6 weeks to fly further north, from Texas to North Carolina and even parts of Virginia. They lay their eggs and die. The 3rd and sometimes even a 4th generation continues the cycle and the journey north, finishing the spring migration in the southeastern parts of Canada and northern portions of the United States.

Then the fall migrators emerge. They are in a state of diapause, not mating and so are able to make the dangerous 2-month journey south to Mexico mostly and some to Florida. On this 1,500-3,000 mile trip, depending on where they began, the monarchs are faced with death daily from predators, disease, extreme weather conditions like storms, geographic challenges like vast stretches of water where staying in flight is critical, and a lack of milkweed to sustain their energy.

When the monarchs finally make it to Mexico they overwinter in the trees of the oyamel forest, clustering together to keep warm. It’s a joyous and wondrous time in the village nearby when millions of monarchs descend and the locals believe their ancestors have returned in late October around “Dia de los Muertos,” or the Day of the Dead.

The Monarchs remain there until about March, when this first generation begins the spring migration north and east to mate, lay eggs and die after an exhausting 8-9 months of life, arguably the longest of any butterfly. And the cycle begins again.

The western population appears to have a similar pattern of generational travel, having a fall migration from Washington, Oregon and the southwestern sections of Canada to the coast of California (some even venturing to Arizona and even the oyamel forest of Mexico.)

But travel routes during the spring migration north and the fall migration south to various overwintering sites are not so defined. And both the migration and the overwintering sites are in danger.

According to Sarina Jepsen, Endangered Species Program Director at the Xerces Society, “There’s an art to preserving overwintering sites. Microclimate change can occur when just some of the trees at the site are cut – affecting humidity, shade, sun and protection from wind.”

Though disease and other natural causes threaten the survival of the monarchs, perhaps the most severe threat is from humans.

In the East, the growing culture of genetically modified crops allow for the mass dumping of harsh herbicides, destroying native milkweed plants, the only breeding and feeding grounds for monarchs.

In Mexico, the monarchs’ overwintering habitats are threatened by deforestation of the oyamel forest.

In the West, our drought problem and urban sprawl destroys the milkweed, hence eliminating the monarch’s only food source.

So it’s no surprise that the monarch population has plummeted. According to the Xerces Society, the eastern population has dropped nearly 90% compared to the highest monarch population estimated in 1996-1997, hitting an all-time low this year.

The western population has seen about a 50% decline (taking into consideration a 17-year average) since 1997 when 1.2 million monarchs were counted. The last count in November 2013 recorded around 200,000.

Though the numbers look bleak, there is certainly a surge of interest in preserving this natural work of art and vital piece of our ecology. And protecting the monarchs’ migration is to protect the monarch itself.

“The more you learn about monarchs the more fascinating they become… Monarch butterflies are also ideal for involving citizen scientists and for conducting research with students. This is especially true in the west where we are still developing a culture of effective citizen science.” says Dr. Francis Villablanca, Professor of biological sciences at Cal Poly, San Luis Obispo, director and research advisor for monarch alert.

So to become more educated and help the monarch population recover, try some of the unique activities below.

Visit an overwintering site October-February. There are hundreds along the California coast, from Mendocino County to San Diego, the only place to see overwintering monarch in the United States. According to Dr. Villablanca, “Two of the most spectacular sites are Elwood Main in Santa Barbara, and Pismo Beach State Park.” Another popular site is around the Pacific Grove Museum.

Become a citizen scientist during the Thanksgiving count and help field researchers determine the total number of monarch (October-January).

Learn how to get involved in tagging monarchs and furthering the study of migration patterns.

Visit a vivarium (a house of butterflies) Go to for year-round visits. Or enjoy the butterfly pavilion at the Natural History Museum (April-August)

For a fun family activity in your own yard, create a milkweed garden and become a feeding and breeding waystation for spring migrators headed north., and

Visit my blog for more information on monarchs and to read about my experience raising and releasing monarchs in our home in the San Gabriel Valley.

A special thanks to those who shared their passion for and wisdom about monarchs: Angie Babbit, Pat Flanagan, David James, Sarina Jepsen, Gail Morris, Dr. Robert Pyle and Dr. Francis Villablanca.

Originally published in the Fall 2014 issue of The Quarterly magazine.

By Ann Suk Wang

Raising Monarchs

Step 1: A monarch feeds on milkweed and lays her eggs
Step 1: A monarch feeds on milkweed and lays her eggs

This past spring I witnessed the beauty and mystery of monarch butterflies in my garden. At first, I was skeptical any would flutter by. How would they find my two small milkweed plants?

When they did find it, I was concerned about my lack of ability and time to raise them. Now that I’ve come out the other end, I can say for certain that with a little guidance and effort, anyone can do this. And it’s worth the effort!

As autumn approaches, the western monarch butterflies migrate south, from parts of Northwestern US to various forests along the coast in California, where they overwinter, bundling together to stay warm for survival.

This is not the season for raising monarchs, but rather, it’s a time for preparing your milkweed for the spring mating season and migration back north. You may also choose to buy more mature milkweed plants in early spring.

The western migration pattern for the monarchs differ from the more well-documented eastern migration from Canada and northern United States to the oyamel forest in Mexico. Though the butterfly species are the same, the ones on the West Coast overwinter in different areas than their eastern counterparts.

The overwintering sites are at their peak from about October-February. There are hundreds along the California coast, from Mendocino County to San Diego. According to Dr. Francis Villablanca, Professor of Biological Sciences at Cal Poly, San Luis Obispo, Director and research advisor for Monarch Alert, “Two of the most spectacular sites are Elwood Main in Santa Barbara, and Pismo Beach State Park.” Another popular site is around the Pacific Grove Museum. For more information, visit:

But if you would like to experience monarchs in your own home, begin by growing milkweed in your garden. By spring they should be full and at least 1.5 feet tall (or purchase two or more 5-gallon container plants). This way, the monarch larvae have plenty to eat. Native varieties are best. But an easier plant to maintain is the tropical milkweed. It’s a beautiful water-wise plant, too — though poisonous to ingest, like most milkweed. Just make sure to cut it down during the off season (starting in late July and August) to help minimize passing on disease to future monarchs and allowing for a more natural migration pattern.

Step 2: A very hungry monarch caterpillar (larva)
Step 2: A very hungry monarch caterpillar (larva)

When spring comes, the overwintering monarchs will be ready to mate and head north. Their migration is truly a unique phenomenon that is still a mystery to many scientist. It will take at least 3 generations of monarchs and about 4 months to make it all the way up. And it is during this time when the monarch-raising fun begins!

1) In late spring especially, stay vigilant every day (even just 15 minutes in the afternoon), visiting your milkweed plant, killing aphids with a swab on a stick dipped in alcohol, and watching for drifting monarchs. Chances are, these monarchs will land on your milkweed and leave eggs behind. If you’re patient and watch closely, you may even see the monarch actually lay the egg. When I first encountered this, I was moved by the life that was being formed before my very eyes! When you see a white ellipsoid dot on a green stem, you’ve got an egg.

2) 3-4 days later, a tiny caterpillar (larva) will emerge. Keep searching for them daily under leaves and near flowers. When you find one, cut off a small area of the plant, where the larva is hanging on for dear life and bring it in. Be warned… I wanted the larva to live naturally in the garden; but for me, that meant 100% of them being eaten by predators! I was so sad because I felt like the worst monarch mommy. It was time to bring in new hatchlings. And if your plant is healthy, 100% of your larva could successfully emerge as butterflies!

(Note: You may not have time to take care of caterpillars; don’t panic! Just having the milkweed to feed passing monarchs is good! And if you have eggs, you can try to leave them in the garden. You may not have especially dangerous caterpillar snatchers like I did! But if you bring them in…)

mesh dome
mesh dome

3) I put the cut plant (like a straw) into a water-filled plastic cup with a lid, like the ones you get at coffee shop. This helps keeps the plant fresh.

4) I covered the cup/plant/larva with a mesh picnic dome. Whenever the plant looked munched down to nubs, I replaced the plant and gently allowed the caterpillar to crawl onto the new plant. Note: the larva goes through about 5 instars, shedding it’s skin and emerging bigger each time.

In the last few days the larva eat so much, you need to clean their area (to reduce disease) and replace the demolished plant nearly every 18-24 hours. This took the most time in the monarch raising process. Note: Cleaning requires removing the frass (larva excrement) and wiping the flat surface with a natural disinfectant like an equal parts vinegar and water mixture.

5) After the larva can eat and grow no more, they inch their way to the top of your dome and hang upside down in a “J” shape. Try not to disturb the larva from here on! After about a day or two, they will do a circular dance while hanging upside-down. Within minutes a chrysalis will form around the larva. If you happen to catch this process, you will be amazed by the instant transformation. IMG_1173

6) For the next 10 days or so, a dramatic and amazing transformation is taking place inside the chrysalis. (I even felt like my monarchs were teaching me life lessons…  Like sometimes I need to slow down in order to experience deep change… but that’s another article.)

7) When the butterfly is ready to emerge, the chrysalis turns black and then translucent. The shell cracks open and moist wings unravel while fluid is gradually pumped into them,expanding as they dry. Within 10 minutes to a couple hours, the monarch is ready to take flight. You may want to admire the beautiful creature for a day or so; but whatever you do, release it (preferably in the morning or the cool of the day, not at night).

Step 3: jewel-like monarch chrysalis
Step 3: jewel-like monarch chrysalis

8) Often they land on your hand or clothing, as if to say “thank you”  before their final goodbye. And when they leave, you ‘ll feel proud knowing you’ve saved a life and helped the great monarch migration, a natural phenomenon that is still being studied and understood. (Stay tuned for my next post about the monarch migration as it appears in The Quarterly magazine, Fall issue.)

Please share your monarch adventures or misadventures here. I will do my best to answer your questions; but honestly, I am barely scratching the surface on raising monarchs. For a more detailed look into caring for monarchs, try visiting sites like and borrowing related books from your local library.

If you’re not sure whether or not you’re ready to raise monarchs, consider the benefits (invite a lovely display of nature into your home, plant a water-wise garden with milkweed, become a feeding and breeding way station for migrating monarchs, produce much needed pollinators, help save the monarch migration and the monarch itself…) These far outweigh the costs.

Note: Photos are by yours truly. I hope you enjoy them!