National Geographic News

Lindsay N. Smith

National Geographic

Published August 19, 2014

Fewer monarch butterflies are crossing North America to winter in Mexico, and the biggest culprit seems to be the disappearance of milkweed in the United States. The trend is particularly troubling because monarchs have long been considered both an indicator of our ecological health and a representative of pollinator populations.

Monarch butterflies travel up to 3,000 miles each fall to their wintering site in central Mexico, which was discovered by National Geographic grantee Fred A. Urquhart and his team in 1975. Once the butterflies arrive, a census by citizen scientists estimates how many have completed the trip.

In 2004, an estimated 550 million completed the winter migration, while in 2013 only 33 million arrived. Further, between 2012 and 2013, there was a 43.7 percent decrease in the area occupied by the butterflies in their winter sanctuaries. (See "Monarch Butterflies Hit New Low; 'Worrisome' Trend.")

Monarchs in peril

Monarchs migrate up to 3,000 miles each fall to their wintering area in central Mexico. In the past few years citizen scientists have recorded a sharp drop in the number making the trip.
Map of monarch habitat
NGM MAPS. SOURCE: JOURNEY NORTH

Although illegal deforestation and severe weather have contributed to the decline, research done by the World Wildlife Fund Mexico and the Monarch Butterfly Biosphere Reserve suggests that the overwhelming concern is U.S. farms' large-scale use of herbicides that destroy milkweed. Further studies done by D. T. Tyler Flockhart, of the University of Guelph in Ontario, and his colleagues compared the relative effect of each threat and determined that loss of milkweed had the greatest impact on recent monarch declines.

Milkweed is the only plant on which monarch butterflies will lay their eggs, and it is the primary food source for monarch caterpillars. Despite its necessity to the species, the plant decreased 21 percent in the United States between 1995 and 2013. Scientists, conservationists, and butterfly enthusiasts are encouraging people to grow the plant in their own yards and gardens.

The butterflies' life span is so short that those making the next migration to Mexico will be the great-grandchildren of the previous migrators. For this winged orange icon, survival is a group effort.

35 comments
Joan Charles
Joan Charles

The rhythm of nature seems quite altered this year. A second group of Monarchs appeared after I released the first group from August 18th. I just released them this morning, September 20. I have never release them this late. Now I am wondering if they are heading North or South!

Rose Anderson
Rose Anderson

If anyone here has any insights on this, I'd greatly appreciate it. One of our biggest issues here in Maryland is mowing of field habitats. The ideal mowing schedule for maintaining these is typically mowing once very three years in the very early spring before field birds nest (to prevent reforestation), but this year I was horrified to find that it had been done in early July. Thousands of wild milkweed plants were destroyed. 


By law, invasive thistles cannot be allowed to go to seed, and I'm told this is why the mowing was done when it was. So we have a serious issue, and I'm on a new committee to investigate and try to solve this. Not only do we have to work out how to proactively control the invasives so that mowing will not be required, we need to figure out how to get county land management and all of the various mowing contractors on the same page. 


What I am looking for is an example of an area where similar issues were successfully resolved so we can implement a plan as soon as possible. Does anyone know of a county/state where field habitat management best practices have been successfully implemented at a political level?

Robyn Orban
Robyn Orban

Around 1972 on Devereaux Beach (near Santa Barbara CA) I was riding a horse bareback, and turned him toward a grove of trees. We walked into shadowy air that fluttered, bright, dense with soft, impossibly delicate powdery orange and black living mosaics. They  incredibly gently but rhythmically buffeted my skin... tiny soft strong wings...  tickly  feet.  The sound of so many thumping little wings and bodies...so many thousands.  My horse and I,  entranced, stood quiet, gazed,  insulated from the world for those moments... a maelstrom of Monarchs churned the air... made magic.

Joan Charles
Joan Charles

I live in Hampton, the tidewater area of Virginia. I have a small stand of milkweed beside my house that has been there since 1990. Three years ago I had 44 eggs; two years ago, 22; last year 11; this year 3. And each year they have shown up a few days later than the year before. This year they came August 18. I do worry about them.

Carole Johnson
Carole Johnson

Thanks for all of the great information.  We have had some monarchs here in the Atlanta suburbs in the past years.  This year I planted two varieties of milkweed and had a couple of volunteers.  The volunteers have already bit the dust and the planted ones have gone to seed.  I usually see caterpillars by now, but nada and now the milkweed is spent.  We will soon be moving to planting zone 5b in Utah.  Any suggestions for next year?  

hank steel
hank steel

 It is a magical wonder that any butterfly can survive a flight through the mass of humanity and all the development from the United States to Mexico. May be we can just catch the butterflies before they migrate and safely truck them to Mexico for the winter. In the spring bring them back to the U.S.

Marisol Barrios-Moyer
Marisol Barrios-Moyer

I'm hosting a live 24/7 webcam showing a pair of monarch caterpillars and their eventual transformations. If you're interested, please tune in and share it with others! I'm planning on adding videos this year teaching others how to raise monarchs for themselves. Every person that raises monarchs makes a HUGE contribution with every single one since they have a nearly 100% survival rate when being raised but a less than 10% chance in the wild. Please check out my webcam! http://www.ustream.tv/channel/monarch-monocle

Cynthia B.
Cynthia B.

I tried gathering some of our typical milkweed seed last year but it didn't take off. I will try again. However, it looks like the orange milkweed I found later this summer is rooting well (& gorgeous to boot). The bees and other butterflies have loved my coneflowers/echinacea this year and it is THE easiest thing in the world to grow from seed...along with my zinnia that they also love. They spend more time on those plants than my butterfly bushes.  I work full time so I have to foster low maint plants. Just buy the seeds (try seeds.com) and stay away from garden centers dousing in pesticides. Even some of the more common seed manufacturers are guaranteeing their seed. Burpee, I believe, is one. Check their websites if unsure. 

Cynthia B.
Cynthia B.

I had a garden full of them last year (S VA). Yesterday I just saw my first for the entire summer. Very sad & scary. I hope people are waking up to what we are doing.

s b
s b

Yup. This is the 3rd summer (year) in a row where I have NOT seen a single Monarch Butterfly in my yard here in Maine.  I have large section of my yard that I mow once a year....in the late fall.....and to keep it wild, reduce my own carbon footprint,  and yes,  there is some milk weed.  


We Americans are great for the senseless harvest of green lawns each and every week.  Approx. 5% of the air pollution in the US comes from lawn mowers!   Imagine if we reduced the size of our lawns and mowed less frequently!


Imagine having wild areas in our yards that could include such plants as milk weed! 


No doubt that the US agriculture giants are destroying our land....but we home owners also share some of the blame.  Reduce the size of your manicured lawn....and plant wild flowers!

Tommy B.
Tommy B.

Looks like I'll be planting some Milkweed in my yard.  How about you?

K.C. Williams
K.C. Williams

Last summer, my daughter was 6 years old, and she started talking about the fact that she wasn't seeing any butterflies anymore.  Later that summer, we went to a butterfly farm, and learned about the disappearing milkweed. This is the first time I've seen an article about it.  Thank you so for making everyone aware. 

James Schuessler
James Schuessler

Just saw one this afternoon in my backyard in Maryland. Used to see loads of them every summer about 10 years ago, now I'm lucky if I catch a sight of one.

Christian Johnson
Christian Johnson

We welcome you to visit the Save Our Monarchs (www.saveourmonarchs.org), a new foundation established to bring back our monarch butterfly. Visitors can order free milkweed seeds directly on our website! You can also donate to our cause if you wish.

Ellen Baggett
Ellen Baggett

I live in North Florida. Normally I have many Monarchs. This year they are very very sparse. I let milkweed seed all over my backyard with no pesticides. I am worried.


Seamus Cameron
Seamus Cameron

"Although illegal deforestation and severe weather have contributed to the decline,"

I'm going to call BS on that. In my little corner of the world , 80 acres in Northern Michigan, once one of the most heavily 'weeded' areas of the country it is 'Reforestation' that is killing off the Milkweed. My land hasn't been farmed for 80 years and there used to be tons of Milk weed, but as the forest has slowly begun to reclaim a patch of ground here and one there the Milkweed has disappeared and so have most of the Monarchs.

The ever lowering of standards of Journalism and integrity in favor of Buzz-word group think at NatGeo has truly destroyed a once great publication.

Benjamin Vogt
Benjamin Vogt

Loss of prairie. The main production areas are NE, SD, IA, MN, WI, and IL. But especially IA, where something like .1% of prairie is left. With the farm bill still favoring ethanol and a cut in crp funding, the incentive for farmers is to put former crp lands back into moncultures and keep carving up what little they can -- from farming up to the roads to taking out bee-friendly shrub and tree hedges. What, 70% of corn goes to ethanol?

David Sanders
David Sanders

Thank you Paul and Carol1


we live in NW Wisconsin on one of the great rivers in the State. We intentionally planted and let Milkweed grow in and about our natural plant gardens and along the river bank. This year there has been an abundance of Monarchs to enjoy!

Paul Cherubini
Paul Cherubini

The Monarch Butterfly is not hardly in peril. Ten days from now I will be posting many Youtube videos of hundreds upon hundreds of monarchs gathered at dozens of different spots near and among the GMO corn and soybean monocultures in southern Minnesota and Iowa.  The number of recorded overnight roost sites in the Midwest in 2014 will be similar to the number recorded in 2010.  I have a BS degree in Entomology from UC Davis and have studied the monarch migration for 49 years.

Carole Steinfeld
Carole Steinfeld

They should grow Calotropis gigantea (Crown flower) from Hawaii ... that's what the monarchs eat over there, because there's no milkweed.

Jessica Detrick
Jessica Detrick

@s b Unfortunately some of us don't have a choice in how often we mow. Many cities have ordinances and will fine you if you're grass is too long.

Paul Cherubini
Paul Cherubini

@s b In Iowa, where 69% of the State's entire landmass is covered with monocultures of GMO corn and soybeans, monarchs are very abundant this summer:


"I have recorded seeing at least one monarch every day for the last 4.5 weeks!! Sometimes I have seen as many as five in a day. This has not happened in at least 20 years! I really hope that our fall migration numbers follow these trends. It is also the only year I can remember collecting more than one or two eggs. This week, I have collected eight. Good to hear all this news from this central region." –Jim and Linette Langhus, Monona Iowa

Paul Cherubini
Paul Cherubini

@Benjamin Vogt prairie milkweeds are full of predators so monarch caterpillar survival is poor as compared to survival on milkweeds growing in the farm road ditches.  Remember this is the Youtube era so all these facts can be documented with video.  

Kar Nels
Kar Nels

@Paul Cherubini  Can someone explain this to me, I have a house on a small urban lot with lots of trees in St. Paul MN, I planted up my whole front and side yard perennials (mostly natives) and have a couple of rain gardens that my roof water dumps into. Tho I don't much like it, I planted milkweed in sever bunches in the yard. I have never seen a monarch on it but I have seen monarchs on cone flowers. Every monarch pic I have seen from gardening friends on FB is on cone flowers - they are popular and hardy here, but these gardeners have all kinds of flowers in their gardens. The bees really love other things like my Anise Hysop.  I walk thru yard several times a day and spend chunks of time weeding out there, never seen a monarch on the milkweed.

Benjamin Vogt
Benjamin Vogt

@Paul Cherubini Sure, the butterfly is not in peril, and maybe the eastern migration will last -- but do you really think it will, what with climate change influencing both the wintering grounds and the midwest production areas? Isn't the larger issue here more about total ecological health, and perhaps even ethical?

Elise Villemaire
Elise Villemaire

@Paul Cherubini @Benjamin Vogt The corn and soy monocrops of the Midwest are now almost all "roundup-ready" and are so deeply soaked in the the poison, even farm roads are now devoid of the Monarch-critical weed. This is side-by-side with the unavoidable neonicotinoid "seed coatings" that add to the damage of both beneficials and water supplies.

It's a a GMO monocrop/agribusiness-as-usual double whammy. Not only do we risk our Monarchs and bees etc. from the pesticide soup, but we have such overly (and at the wrong time) fertilized monocrop fields where human communities on the Great Lakes have to worry about phosphorous-fueled poisonous algae bloom-and-bust cycles and needing to turn off their water on a dime to protect "human" lives.

David Henderson
David Henderson

@Kar Nels @Paul Cherubini The adult monarchs (ie, the butterflies) eat nectar from a variety of sources, including cone flowers.  However, they will only lay eggs on milk weed and the caterpillars will only eat milk weed.


The Eastern Swallowntail butterflies have a similar behavior.  The adults eat nectar from a wide variety of sources, but they only lay eggs on plants in the parsley family and the caterpillars only eat the same.

Paul Cherubini
Paul Cherubini

@Benjamin Vogt @Paul Cherubini Migratory Monarchs tolerate a broad range of temperatures both at the summer breeding grounds and winter overwintering grounds.  Evidence: they're breeding right now in the vast area of the Midwest between southern Manitoba and central Texas.  They overwinter on the west coast between Ensenada, Baja California and the northern California coast even though the former is considerably warmer and sunnier.

Benjamin Vogt
Benjamin Vogt

@Paul Cherubini What about cold rains in MX? I'm not just talking temps. This is an incredibly nuanced problem we can't begin to address here. 


Elise Villemaire
Elise Villemaire

@Benjamin Vogt @Paul Cherubini Science author Barbara Kingsolver has written an only slightly preachy, yet delightful novel set in Appalachia dealing with just that question of when a chilly and wet local mountain is suddenly forced to stand in for a lost forest in Mexico. Filled with wonderfully complete science, too.

It's named "Flight Behavior" and is a very fun and fast read.

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