If you live where monarch butterflies breed, growing native milkweed is the first step. Find out what else you can do as a gardener to support the entire lifecycle of these astonishing creatures.
Hummingbirds are another bird that migrates solo over incredible distances. See our hummingbird migration map here to track their progress in spring.
Monarchs & Gardening
For those of us in northern climates, it’s a welcome sight to see the first monarchs arrive for the summer.
With so much discussion about population declines in recent years, gardeners have stepped in to do what they can to provide the habitat these butterflies need to support their survival as a species.
As you’ll see, while absolutely vital, providing milkweed is just one part of the puzzle. Like all living things, it takes a healthy, diverse ecosystem to sustain life.
And, by doing what’s best for monarchs, we’re also doing what’s best for nature as a whole.
- How to Help Monarchs
- All About Monarchs
- Fall Migration
- Spring Migration
- Threats to Monarch Populations
How to Help Monarchs
Many of us welcome monarchs to our cold climate, northern gardens during the summer months where they breed and later prepare for the great fall migration.
With concerns about declining populations and environmental issues, gardeners can use these tips to help support these wonderful creatures—and nature as a whole since it’s all interconnected.
- Grow hardy milkweed plants recommended for your specific region. The reason there is so much emphasis on milkweed is because it’s the only plant monarch larvae can feed on. And without these larvae (caterpillars), you won’t ever have adult monarch butterflies.
Avoid tropical milkweed species, spreaders of harmful parasites including Ophryocystis elektroscirrha (O.E.).
We have a guide for growing milkweed here.
- Grow a diverse selection of native, nectar-rich flowering plants. This is the food that adult monarchs survive on.
Be sure to include fall-blooming plants which provide fuel for the fall migration. Asters, goldenrod, and coneflowers are all good options.
- Grow an assortment of native trees and shrubs to provide places to roost and shelter from the wind and rain.
- Avoid pesticides and herbicides. Gardening for wildlife means letting the food web do its thing.
- Provide fresh water. Mud puddles and ponds do wonders for life in the garden.
- If you travel to see migrations or other natural wonders, learn about best practices for eco-tourism that put conservation first.
These days, with so many incredible photos, videos, maps, and satellite views available online, staying home may be the best option.
- Speak up. There are countless ways to put your support behind eco-beneficial efforts. Support organizations with your same goals. Vote. Write your politicians. Protest. Learn all you can. Share what you learn. Heed the inner call and go for it.
This is a contentious issue and for good reason. While it sounds helpful to raise and release monarchs to increase populations, raising monarchs in captivity raises various concerns including the spread of disease, genetic issues, and just how effective it is in the long term. Without a lot more research, we do not know if direct human intervention will truly help. After reading the arguments for and against captive rearing, I personally would not do it, no matter how enticing or educational it seems.
Now that we’ve covered the support tips, let’s jump into the wonderful world of monarchs.
All About Monarchs
Of all the migrating animals here in North America, monarch butterflies, like hummingbirds, have one of the most interesting life stories.
You can read more about hummingbird migrations here.
Not only do monarchs complete two-way migrations each year—one in spring and the other in fall—but these journeys often cover thousands of miles each way.
That in itself seems astonishing for such lightweight, little creatures with tiny brains, but there’s more.
Monarchs migrate with no prior experience.
It’s always a new generation that completes these treks—each monarch flying the route solo on its own for the first and only time.
For Eastern monarchs on the central migratory route, this can mean flying all the way from Canada to a specific mountainous region in central Mexico.
They don’t have older, experienced monarchs to lead the way. It’s just a new generation of monarchs, each using its internal compass and circadian clock, instinctively navigating where it needs to go.
The word “amazing” is seriously overused but this really is just that.
Monarchs in North America
Monarchs (Danaus plexippus) in North America have two basic populations (with some crossover):
- Western Monarchs | Live west of the Rocky Mountains and winter along the Pacific coast in California
- Eastern Monarchs | Live east of the Rockies, with many of their descendants overwintering in a small part of Mexico and others in Florida.
A quick overview of the monarch lifecycle helps us understand what they need at each stage of life.
Complete Metamorphosis: egg -> larva -> pupa -> adult butterfly
Weather extremes can always throw off these timelines but these are generally how it goes.
- Adult monarch lays eggs on milkweed leaves.
- Monarchs emerge from eggs as larvae (caterpillars). This stage typically lasts a week or two.
- After bulking up on milkweed leaves, the caterpillar pupates to form a chrysalis. The chrysalis stage also lasts a week or two.
- When ready, the new adult emerges from the chrysalis as a butterfly. And off it flies.
Low Survival Rates
When it comes to reproduction in the natural world, it takes a lot to make a few.
With so much attrition, many species have to produce multitudes of seeds or eggs to ensure some survive.
And monarchs are no exception.
Harsh weather, predators, parasites, and other factors all pose a threat.
- For all the eggs they lay, most monarch caterpillars die within a day of coming out of the egg.
- From there, an estimated 90 to 99 percent will die before becoming adults (butterflies).
- The survivors that do make it to adulthood are a scant 1 to 10 percent that beat the odds.
Toss in climate change, herbicides, pesticides, and loss of habitat, and the chance of survival lowers.
There are three main migration groups:
- Western monarchs that (mainly) stay west of the Rockies and winter in the west.
- Eastern monarchs that migrate south along a central flyway to Mexico.
- Eastern monarchs that stay along the Atlantic coast and winter in the southern US including Florida.
Let’s have a look at the fall migration of Eastern monarchs that follow the central flyway.
Here in the Great Lakes region, around late August to mid-October, the monarchs start heading south.
Like hummingbirds, monarchs do not fly in flocks. It’s more like commuters each travelling at the same time to the same destination.
Daily distances average around 20 to 30 miles per day but there are also records from tagged monarchs that managed to fly hundreds of miles in just a few days, likely assisted by strong back winds.
Migration takes place during daylight hours and they rest at night, sometimes roosting together on tree branches in numbers great or small.
Some roosting locations are used year after year and become butterfly tourism destinations—like Point Pelee National Park here in Ontario.
Monarchs that complete the winter migration can live as long as 8 months total—far longer than their parents, grandparents, or great grandparents ever did.
There is no reproduction during the journey south—they just need to get to their winter home ahead of oncoming freezing weather in the north.
The Once-Secret Winter Home
While Indigenous people of this part of Mexico have most certainly long-known where monarchs overwinter, no one else knew—or they all kept the secret—until National Geographic revealed it to the world in their August 1976 issue.
The cover story, “Found at last: the Monarch’s Winter Home” was quite a sensation.
You’ve probably seen some of the photos with masses of monarchs covering every square inch of oyamel fir tree branches. There can be upwards of 6200 on a 5-foot tree branch. That’s 80 pounds of monarchs!
Multiply this by millions and sometimes hundreds of millions of monarchs that overwinter there and it’s quite a gathering.
Back in 1976, the team that found the site tried to keep the exact location under wraps. The map with the story was not very precise. They did not even want to tell other researchers, which created some friction.
It took a few years, but eventually others figured out the location.
Today, you can Google the Oyamel fir forests of Central Mexico and view a 3D satellite map of the area.
We might expect a winter home in Mexico to be fairly warm but this is on the cool side with temperatures hovering around 40 to 50°F (5 to 10°C).
Monarchs cannot fly unless their flight muscles are 55°F (12°C) or warmer so much of the time is spent resting.
As temperatures warm in the new year, the butterflies wintering in Mexico become more active and start the great spring migration to their breeding grounds.
The first destination on the journey north may be in Texas or Oklahoma and sometimes as far as the Midwest.
There is a link in the Resources section where citizen scientists report their first sightings of the year.
What makes this migration possible, and perhaps what drove it in the first place, is the availability of milkweed.
Monarchs lay their eggs on milkweed leaves because that’s the only plant their caterpillars will eat.
These plants contain toxins that do not harm the monarchs but, when ingested by the caterpillars, make the monarch toxic to some predators. The orange and black coloring of the adult butterfly is code for don’t eat me—I taste awful!
This is, however, a one-sided relationship. Monarchs need milkweed but milkweed does not need monarchs. Instead, monarchs pollinate other flowering plants while collecting nectar.
While milkweed is vital to monarchs, it’s important not to lose the bigger picture. It won’t really help to have larvae in the ecosystem if our environment does not sustain adults as well.
While just one monarch generation makes the long journey south for the winter, the journey north in spring is multi-generational.
- Generation 1 overwinters in Mexico and then travels into the United States in spring where it lays eggs on milkweeds.
- Generation 2 emerges from those eggs, morphs into adult butterflies, and continues the journey north where it too lays eggs on milkweeds.
- Generation 3 emerges from those eggs, and on it goes. Each of these generations lasts perhaps a month.
- Generations 3 or perhaps 4 arrive in their summer breeding grounds as far north as Canada. Depending on how many generations the journey required, these may be the great- or even great-great-grandchildren of that original generation from Mexico.
And their offspring become the new Generation 1 who will migrate to Mexico for the winter and eventually head north again in spring to start the cycle all over again.
Threats to Monarch Populations
Monarchs face a range of challenges—both natural and human-caused.
Extreme weather including unusually hot, cold, and rainy periods, along with natural predators, are detrimental. Parasites are also a big problem.
Threats to Winter Habitat
- The specific, small part of Mexico where monarchs overwinter has been shrinking in size since the late 1990s.
- The trees monarchs roost on are an essential part of the local fir tree logging economy.
- These mountainous forests as a whole are degrading, which may be related to climate change.
- Monarch tourism, while helping support the local economy also brings conservation issues.
Threats to Spring & Summer Habitat
- Milkweed numbers along spring migration routes have declined in recent years. This loss of habitat has coincided with the expanded use of glyphosates on farmland.
- It was this decline that sparked the whole Save the Monarchs movement, encouraging gardeners and conservationists to plant milkweed to offset these losses.
- Journeynorth.org | Lots of monarch info and maps to view and report sightings
- Science.org – The Plan to Save Monarchs Backfires: The wrong kind of milkweed is stoking parasite infections
- How to Grow Milkweed & Save Seeds
Want Pollinators in Your Garden?
- Choose plants, trees, and shrubs used by local wildlife for food and habitat during all stages of life. Options will be different in each growing region.
- Avoid products like pesticides that are toxic to pollinators and other animals in the food chain.
- Keep it natural: sustainable gardens are not tidy. Dead and decaying things nourish living things.
You can read more ecological gardening tips here.
Monarchs Around the World
Monarchs arrived in Australia, New Zealand, and nearby areas in the 1800s. We’re not entirely sure how they got there but they are common today. They were able to colonize because suitable milkweed species from other parts of the world had already been established.
You can also find monarchs in parts of Spain and Portugal, mostly in the last 30 years.
There are occasional sightings in the United Kingdom, but those are monarchs that got blown off course or hitched a ride and not part of a stable population.
What’s the butterfly that looks like a monarch?
The viceroy butterfly (Limenitis archippus) is most similar to the monarch, although smaller in size. Each hindwing of the viceroy also has an extra black stripe.
~Melissa the Empress of Dirt ♛