Claim: We’re losing monarchs fast—here’s why

From National Geographic

A new study finds that monarch wings are getting larger, possibly because climate change has forced the butterflies to travel longer distances as breeding grounds shift farther north.

Monarch’s at Pacific Grove, California. Credit: ctm

It’s not too late to save them, but it’s a question of whether we make the effort, scientists say.

6 Minute Read

By Carrie Arnold

PUBLISHED December 21, 2018

The epic 3,000-mile monarch butterfly migration may become a thing of the past. Each fall, monarchs travel from their summer homes in the northern U.S. and Canada to winter habitats in California and Mexico. But the 2018 Western Monarch Thanksgiving Count found that the number of west-coast monarchs spending the winter in California had plunged to only 20,456 butterflies—a drop of 86 percent since last year. And the number of eastern monarchs overwintering in Mexico this year has dropped 15 percent since last year, for a total decline of more than 80 percent over the past 20 years, according to the National Wildlife Federation.

“A lot of environmental threats can pile up on top of each other,” says University of Wisconsin entomologist and director of the UW-Arboretum Karen Oberhauser. And the consequences can be hard to predict.

Although monarchs teeter on the edge of an extinction tipping point—in which their numbers drop too low for the species to recover—scientists like Obserhauser say all is not yet lost. Creating new monarch habitat by planting native milkweed species may provide crucial fuel and rest stops for the traveling butterflies, as will taking more action to address climate change.

Monarch’s at Pacific Grove, California. Credit: ctm


A 2004 email from a Midwestern farmer first alerted Kansas University entomologist Chip Taylor to the pending monarch apocalypse. The creation of herbicide-resistant corn and soybeans meant that farmers could eradicate weeds and other understory plants, including milkweed, that competed with their crops.

The invisible hand of fear and dread gripped Taylor’s gut. He had spent years studying monarchs and knew they depended on the milkweed studding their migratory corridor across the Midwest. The advent of these new crop varieties meant the death of milkweed.

Data over the next few years only confirmed Taylor’s worst fears: monarch numbers began to plummet. “In a very short period of time, monarchs took a tremendous hit, with tremendous consequences,” Taylor says.

Monarch’s at Pacific Grove, California. Credit: ctm

In addition to the loss of milkweed across farms, drought also harms milkweed quality. A 2013 drought in Texas decimated milkweed there, which contributed to low monarch numbers that year.Nectar-rich flowers are important for monarchs’ continued survival. And milkweed, the only plant monarch caterpillars eat, is especially important.The loss of milkweed has clued in an increasingly concerned public that the beautiful butterflies they love might go the way of the passenger pigeon and the woolly mammoth. Awareness of vanishing milkweed bled over into fears of how monarchs would fare as the climate continued to change. A series of papers in the last few years shows that these worries were not misplaced.


Rising carbon dioxide levels from the burning of fossil fuels sit at the heart of climate change, and this increase of carbon can alter how plants like milkweed build certain molecules, explains ecologist Leslie Decker, a postdoctoral researcher at Stanford University. Milkweed produces toxic steroids called cardenolides. The monarchs have evolved in a way that allows them to tolerate low levels of this poison, storing it in their bodies as a bitter-tasting deterrent to predators.

Models predict an 11 to 57 percent chance that monarch numbers would drop so much in the next 20 years that the species wouldn’t be able to recover.

Cardenolides also help the butterflies by impeding the growth of a monarch parasite with the tongue-twisting name Ophryocystis elektroscirrha. “I had to practice pronouncing this when I was in grad school,” Decker laughs.

The single-celled parasite can infect newly hatched caterpillars by drilling holes in their gut to replicate. If the caterpillars survive, the resulting butterflies have misshapen wings and lowered endurance. Cardenolides help the monarchs tolerate the parasite so that it doesn’t harm them.

But when Decker grew milkweed in a greenhouse with carbon dioxide levels of 760 parts per million (ppm)—what climate scientists project will happen in 150 to 200 years as the current level of 410 ppm continues to rise—she found that the plants produced a different mix of cardenolides, one that was less effective against monarch parasites. She published her findings in July 2018 in Ecology Letters.

“We don’t know how we’re changing the green pharmacy around us,” Decker says.

Read the full story here



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Jon Scott
December 27, 2018 10:06 am

So what did they do during the Medieval Warm Period? Utter utter unsubstantiated speculation.Since when was speculation part of the scientific method? Assertion without statistically significant empirical data to support is is just that. Alarmist Rubbish!

Reply to  Jon Scott
December 27, 2018 12:11 pm

The MWP is evidence that the current warmth is not unprecedented. That’s not really the problem here.

This is a continuation of the ‘enhanced CO2 makes plants less nutritious’ meme. The problem with that is that greenhouse growers use enhanced CO2 with food crops with no noticeable loss in nutrition content. link

Javert Chip
Reply to  Jon Scott
December 27, 2018 12:12 pm

This is the age of “Millennial Science”

o Feelings, not a well articulated, falsifiable theory is what counts
o There are safe spaces from having to face reality
o We’re spending other people’s money, so ethics be damned
o Scientific opinions of people who wouldn’t know a differential equation if it bit them in the ass (especially psychologists,) are every bit as valid as dudes with physics PhDs (especially if the PhDs are skeptics)
o Facts do matter, as long as they are ours
o Of course we don’t want to beat anybody up or throw them in jail simply for their opinion … ooops … scratch that
o The cumulative IQ of the 97% of us that believe this is the way to proceed is less than 97

Reply to  Javert Chip
December 27, 2018 2:16 pm

Maybe it’s postmodern education in general. Camille Paglia notes the death of overview courses in the arts because there is nobody with sufficient breadth of knowledge to teach them. link

Time after time, we see papers published that contradict well known and widely confirmed facts. In this case, as I observe above, we have a ton of papers asserting that extra CO2 will reduce the nutritional content of food crops. That is in the face of the fact that greenhouse growers routinely enhance CO2 to increase yields and there is no evidence that their crops are less nutritious.

There is the old joke about PhDs who know more and more about less and less until they know everything about nothing. link A scholar who doesn’t know how her subject fits in the context of the greater world isn’t much of a scholar.

Ben of Houston
December 27, 2018 10:10 am

Well, the answer is simple. Plant Milkweed. The plants are extremely resilient to drought and work very well in front yards everywhere in Texas at least. The only problem is that if you plant milkweed in your garden, Monarch caterpillars will arrive everywhere and eat almost the entire plant.

Dale Monceaux
Reply to  Ben of Houston
December 27, 2018 10:27 am

The wife and I have several milkweed plants in our English garden. The first year we hatched about five monarchs. Since then, none. Not sure why.

Big T
Reply to  Dale Monceaux
December 27, 2018 2:59 pm

Monarchs were plentiful here in northern Michigan

R Shearer
Reply to  Big T
December 27, 2018 4:59 pm

Those must be very hardy.

Reply to  Ben of Houston
December 27, 2018 1:25 pm

The monarch is COMPLETELY DEPENDENT upon the milkweed plant for its entire life cycle. The milkweed grows back pretty quickly. I have a few plants and the larvae ate them all up, so only the stalks were left, then they disappeared. (I hope they weren’t eaten!) but the milkweed grew right back, within weeks! (North Florida)

Reply to  Ben of Houston
December 27, 2018 1:49 pm

You do have to thin the eggs. Remove all but one visible egg (it’s my thought you’ll never remove all of them, I say leave one just in case you do find them all but you’ll probably have as many as 6 hatch) so they don’t denude the plant and then starve before they reach maturity. I can confirm from experience that only 3-4 caterpillars/per plant are too many.

Jim of Colorado
Reply to  Ben of Houston
December 27, 2018 5:13 pm

Agreed! More milkweed to offset losses from herbicides is the most likely answer.

Pop Piasa
Reply to  Jim of Colorado
December 27, 2018 8:12 pm

How about Glyphosate-resistant milkweed?
Would it give the butterflies cancer?

guido LaMoto
Reply to  Ben of Houston
December 28, 2018 3:19 am

Loss of habitat/ milkweed in N. Am. is only a small part of the problem. The loss of Mexican forests that support the Monarchs on the southern leg of their life-cycle to make room for the growing of avacados is the biggest problem.

Reply to  guido LaMoto
December 28, 2018 3:14 pm

What! There’s a variable that isn’t in the models which completely invalidates the CAGW science. Blasphemy! Fund 50 times more articles so he’s silenced and invalidated. Whew! Almost let the truth out again. We don’t want that happening.

December 27, 2018 10:12 am

Ah! right.

Lets just introduce milkweed like we encouraged the growth of palm oil plants, to save a butterfly.

A milkweed that’s been ‘tested’ in a greenhouse (read test tube) at 760 ppm with, of course, no external influences on the plant.

What could possibly go wrong?

Reply to  HotScot
December 27, 2018 11:03 am

In these areas, milkweed is a native plant. It’s not an introduced species.

Reply to  MarkW
December 27, 2018 12:08 pm

And there are several kinds of milkweed too.

Jeff Cagle
Reply to  HotScot
December 27, 2018 12:55 pm

Common Milkweed, Asclepias syriaca, is native to the lower 48. It’s decreasing in numbers as farms use roundup-ready seeds, which enable total eradication of weeds via arial spraying.

Oddly, the Maryland DNR has taken to planting milkweed in median strips. Not sure the survival rate of Monarchs that cross the median to lay eggs.

Reply to  Jeff Cagle
December 28, 2018 11:52 am

Here in west MD, there is plenty of milkweed. But there is limited farmland & alot of woodland edges, so I realize the situation might be quite different in areas w/little woodland edges (which are away from the farmers’ herbicides) where the milkweed can proliferate. One thing I do notice tho, is that over time grasses (native and introduced) can choke out not only milkweed but even the mainstay of open, ungrazed fields –goldenrod and asters.

Max Hugoson
December 27, 2018 10:17 am

There is a project, already funded and operated on. It involves planting milkweed in the “median” between the two side (lanes) of I-35, from MINNESOTA to Louisiana.

This helps compensate for the milkweed that has been removed from farmer’s fields because of “universal” application of Roundup, on genetically engineered “Roundup” resistant plants. The YIELDS are much better with this practice, but all extraneous plants are removed. (Milkweed was not considered a big problem in Corn fields, for example. So farmers did not try to get rid of it.)

Reply to  Max Hugoson
December 27, 2018 10:41 am

I-35 does not go to Louisiana. It runs MN, IA, MO, KS, OK, TX

We quit growing corn on the farm from 1988 to 2012 because we needed forage for the dairy cattle and corn was usually cheaper to buy than produce. Prior to 1988 milkweed did not grow in the cornfields, atrazine, a few other herbicides, and cultivation kept the fields pretty clean. Milkweed grew in the fence rows which we still have on the farm but most of the neighbors have removed theirs.

The other thing that changed was the influx of urbanites to development communites that took farmland (and fencrows) out in favor of green desert lawns. And in winter those people complained like crazy when snowy roads kept them from rushing home. So the townships started mowing the ditches more often and in fall will mow almost the entire right of way to reduce snow drift. Time to quit blaming farmers for problems that have a lot of causes.

Reply to  gail
December 27, 2018 11:08 am


Thank you for your practical insight.

Reply to  gail
December 27, 2018 2:03 pm

Salute gail,

Lots more to loss of the milkweed than Roundup [ the new poster child for evil human use of chemicals to increase food produciton for humans, the filthy vermin].

Secondly, we here in the Panhandle of Florida have a great migration of the critters, and not overgrown with milkweed, so I doubt the things only chew on milkweed, though they highly prefer it as another poster in north Florida has witnessed.

Lsstly, I likes this one

climate change has forced the butterflies to travel longer distances as breeding grounds shift farther north

Apparently, the wintering grounds will stay where thay are presently and become living hell, exacerbating the poor scenario for the monarchs. The horror. But wait!!! If the normal flying range of the butterfly is like a rope of “x” length…….? And “gorebull warming” is truly “global”. And we pull the rope to the 30-year basis for anomalies? Wouldn’t the other end of the rope move northward or southward [for SudAmerica and Oz]’

Gums ponders….

Martin Cornell
Reply to  Gums
December 27, 2018 8:43 pm

Gums, you make good points, but know that the eggs of Monarchs are only laid on milkweed and the caterpillars only eat milkweed. Adults consume nectar like other butterflies.

Reply to  gail
December 27, 2018 4:55 pm

gail nails the main issue!

From USA’s Fish and Wildlife department:

“Habitat loss and fragmentation has occurred throughout the monarch’s range.”

1) Small eco units have far more variables involved than just CO₂! Alleged researchers playing with doll gardens are fantasizing.

2) Farmers have never tolerated milkweed growing with their crops!! It is bad stuff to feed animals!

3) Farmers have always allowed fence rows, fallow ground, swampy grounds, etc to grow and provide shelter and food for wildlife

Urbanites and suburbanites are narrow minded regarding plants that harbor wildlife. Many thoroughly detest animals but chipmunks, a few rabbits and a few common birds. After they decimate the insect populations, they’ve knocked off or discouraged birds dependent upon those insects; e.g. bluebirds.

4) Anyone can plant milkweeds

5) Both milkweeds and monarch butterflies have coexisted for a very long time. Childish assumptions and false alarms are not scientific nor do they assist anyone or anything.

From “The Daily Garden“:

“Monarch populations

Traditionally, easter Monarch Butterfly populations have been measured by how many acres of land they cover when they overwinter in Mexico. In 1996-97, Monarchs were estimated to cover over 18 acres (approximately 1 billion butterflies). In 2014, that number had dropped to only slightly more than one-and-a-half acres. In simple terms, this indicates a 96% drop in population. Before we jump to any conclusions, it is important to understand that there have not been comparable drops in summer populations and scientists do not know why.

Monarch butterfly feeding and breeding grounds​
Monarch Butterflies lay their eggs on certain types of milkweed. This is because those are the only plants the larval/caterpillar stage can eat. Popular rhetoric blames herbicides for killing these particular types of milkweed, but many regular Monarch habitats are flush with milkweed – and no Monarchs. There are mixed opinions on why this is and what it means.

As Monarch numbers initially dropped, people became worried and started planting milkweed and nectar plants to provide global corridors of food and habitat for the lovely Monarch butterfly. In less than one year, it was claimed that Monarch populations had risen from 1.6 acres to 2.8 acres as a direct result of these actions. This would be a great story, but it is not that simple. More Monarch populations are being found in previously unused areas. Some Monarchs are not migrating at all, staying where they are and feeding on popular tropical milkweeds that grow year round. Sounds great, right? Well, it is, and it isn’t.

In “normal” easterMonarch cycles, winters are spent in a state called “reproductive diapause”, in which means they are not sexually active. This is caused by hormonal changes that are believed to be related to daylight hours. Since native milkweed plants are dormant in the winter, everything was in equilibrium. The tropical milkweed (Asclepias curassavica) does not go dormant in winter, so Monarchs are able to stay in the same place year round and forego the migration, similar to the Santa Cruz populations. The only problem is, all that continuous feeding has led to the emergence of microbial parasite, called OE for short, that has the weaken significant numbers of an already stressed species…”

Reply to  Max Hugoson
December 27, 2018 11:48 am

Those poor monarchs endure the carnage of crossing the freeway to get to the milkweed in the median…it’s almost like they want to kill them in car grills 🤔

Reply to  Max Hugoson
December 27, 2018 11:51 am

Max H: “… planting milkweed in the “median” between the two side (lanes) of I-35…”

I can just see Monarch butterflies plastered all over the grills and windshields of cars and semi’s.

Reply to  Max Hugoson
December 27, 2018 12:28 pm

It involves planting milkweed in the “median” between the two side (lanes) of I-35,…
…great idea, sorta like baiting deer

comment image

Reply to  Latitude
December 27, 2018 3:19 pm

At least they don’t plant the Moose’s favorite food in the median…

comment image

December 27, 2018 10:20 am

Information from those who actually show they care:

December 27, 2018 10:20 am

We live in Colorado Springs — we usually see few Monarchs during the fall migration. This fall, we had a glut of them. Don’t know if they changed their migration route, or what. We usually see a lot of Painted Lady butterflies instead.

December 27, 2018 10:20 am

A lot of wind farms in Texas. Can’t see a butterfly having much of a chance against those whirly things.

Steven F
Reply to  nc
December 27, 2018 10:38 am

Monarks tend to fly low. well below the lowest tip of a wind turbine. So the wind turbines probably have minimal affect on the population. But that behavior makes them vulnerable to cars.

In the 90’s I was driving south on interstate 5 in California and my car kill a lot. As well as everyone else driving on the road that day.

Reply to  Steven F
December 27, 2018 11:15 am

During migration they are known to fly quite high. For example:

Reply to  Steven F
December 27, 2018 12:49 pm

Turbulence from a passing blade could suck them up higher.

Flight Level
Reply to  MarkW
December 27, 2018 1:41 pm


Reply to  Steven F
December 27, 2018 1:25 pm

and my car kill a lot. As well as everyone else driving on the road that day.
Your car killed everyone…. that is where the problem is.

Reply to  Steven F
December 27, 2018 1:54 pm

…minimal effect…

John Bell
December 27, 2018 10:21 am

“Models predict…” is a red flag. Of course these people do not want to give up any luxuries to save anything, but talking it up is important to them.

December 27, 2018 10:23 am

So loss of milkweed feed is the primary threat to Monarchs, but of course climate change has zilch to do with modern farming practices that reduce milkweed density. But somehow, climate change is suddenly the topic of conversation.

Of course, exposing Monarchs who are adapted to 400 ppm CO2 to a sudden increase nearly doubling that cause a biochemical response. So? If doubling CO2 over the next 150 years is a real outcome, which of course cannot be predicted, there are hundreds of future generations of Monarchs will are most likely to gradually adapt to the gradual increase in CO2 and thereby produce quite different results than this.

Oh, and by the way, changes trace gas concentrations in the atmosphere is NOT “climate chang”e.

Reply to  Duane
December 27, 2018 10:34 am


It was the milkweed they exposed to elevated CO2, not the butterflies.

Reply to  HotScot
December 28, 2018 6:34 am

No – if you read the article, the reduction in milkweed is solely due to modern farming practices such as widespread herbicide usage. The milkweed is not affected by CO2 at all, other than the fact that all plants that use photosynthesis to produce food require and thrive on CO2 which is why greenhouses typically pump more CO2 in to promote plant growth.

The study was clearly pointing to exposing monarchs to a near doubling of CO2 and measuring the biochemical changes in the butterflies.

Learn to read before commenting.

Reply to  Duane
December 27, 2018 11:07 am

I know that spouting nonsense is your forte’, but did you really have to get so good at it?

Sheesh, could you try again, this time with the intention of making sense?

Reply to  MarkW
December 27, 2018 2:59 pm

If your comment is aimed at Duane, then I’m not sure what your point was. With the exception of the doubling of CO2 being tested on the milkweed, not the butterflies, everything he said was correct. And even with the CO2 he was essentially correct. Hell, the experiment has to assume that NEITHER the milkweed or the monarchs can adapt to the raising co2 level over hundreds of generation. It also assumes that somehow in the next century we don’t come up with a better power generation source then burning Fossil Fuels. That seems unlikely to me.


Reply to  Schitzree
December 28, 2018 6:39 am

He’s a kneejerk idiot. He is POd at me because I am not a kneejerk Trump sycophant like he and quite a few other commenters and writers are at WUWT.

WUWT needs to stick to the science, and leave the political propaganda to the right wing media. The more that WUWT focuses on kissing Trump’s butt, the more credibility it loses in defeating climate alarmism. Remember that over 60% of Americans by virtually all polls think Trump is a moron and a loser. Trying to tie him into scientific skepticism of CAGW is the best way to lose the argument.

Reply to  MarkW
December 28, 2018 6:36 am

You’re a kneejerk idiot. Buzz off. My comment whizzed about a thousand feet above your ignorant head.

John the Econ
December 27, 2018 10:25 am

Want to know what is really going to decimate wildlife habitats in North America? The millions of new homes we’re going to have to build to accommodate the millions-to-billions of new residents arriving as a result of our de facto open borders policy.

E J Zuiderwijk
December 27, 2018 10:26 am

Breeding grounds shifting to the north??

Is Point Pelee on the move? Someone ought to warn the Canadians!

Reply to  E J Zuiderwijk
December 27, 2018 8:04 pm

Wikipedia: Monarch butterfly

Monarch butterfly research history in Canada dates back to about 1937.

Article includes photos of Monarch butterfly migration marking to collect information. Also includes many references on Monarchs.

December 27, 2018 10:27 am

Aarghbh! Nothing to do with climate change. Mostly to do with the susceptibility of milkweed to herbicide, and conversion of wild meadows to mowed hay land by farmers.

December 27, 2018 10:27 am

Many thanks for the hat tip.

This article caught my attention as my brother in law lives on the coast just south of Santa Barbara where his dozen or so cliff side trees have in the past easily held 20,000 Monarchs each. The butterfly count was probably low because they were either a bit early or a bit late. These aren’t Capistrano Swallows. Of course this year’s extensive fires might have had something to do with lower and/or disrupted counts.

Reply to  Rob_Dawg
December 27, 2018 10:44 am


Smells all a bit Polar Bear fishy to me.

A bit like the Bee’s that were all going to die and put paid to humanity. But didn’t.

Sniff test methinks.

Reply to  Rob_Dawg
December 27, 2018 1:27 pm

There were exactly “20,456 butterflies” this year in California. There was an 86% drop from the year before (30,084).

Throwing out estimates like “20,000” just shows that your empirical evidence is not be trusted. If you want to establish credence with the California butterfly counting society you need to be (act) more precise; you should say “20,019” or “19,974” to let everyone know that you know what you are talking about. 🙂

Reply to  DonM
December 27, 2018 1:37 pm

There is probably a law in California requiring them to register. That is how they can be so precise.

Reply to  Philip
December 27, 2018 3:11 pm

California knows the number of Monarch butterflies in the state down to the single digits, but can only estimate the number of illegal aliens to within an order of magnitude.


Reply to  Philip
December 27, 2018 6:56 pm

We have a 10 day cooling off period on metamorphosis, so all butterflies must first register with the state.

Andy Pattullo
December 27, 2018 10:36 am

We currently grow increasing yields of staple crops on a reducing land area due to the same mentioned improvements in crop varieties and many other enhancements in agricultural efficiency. This is further aided by rising CO2 and a very slight rise in average temperatures. The result is less hunger and more land left in a natural state where milkweed and other wild plants can flourish. Those wild plants can also benefit from the increasing CO2 and warmth as evidenced by the global greening measure by satellites. In fact the biosphere that supports monarchs is being enriched by the gas that radical environmentalists and hoodwinked policy makers have labeled a pollutant. Perhaps these facts deserve equal coverage to the more alarmist assumptions and guesses presented above.

Reply to  Andy Pattullo
December 27, 2018 11:10 am

Part of the problem has been the increased acres being used to grow corn for fuel.

AGW is not Science
Reply to  MarkW
December 27, 2018 11:26 am

Part of the problem has been the increased acres being UNNECESSARILY used to grow corn for fuel, WHEN THERE’S PERFECTLY GOOD OIL FOR THAT.

There, fixed it for ya (yes, I know I’m “preaching to the choir”).

Bob boder
Reply to  AGW is not Science
December 27, 2018 2:28 pm

nothing crossing the boarder is required to register in California same can be said for Organics

Reply to  Bob boder
December 27, 2018 3:00 pm

Perhaps that was in response to Phillip, above?

Andy Pattullo
Reply to  MarkW
December 27, 2018 4:06 pm

Yes. Complete waste of land, no environmental benefits and makes food more expensive for those who can least afford it. Every day politicians fail to fix this is a travesty.

Reply to  Andy Pattullo
December 27, 2018 11:52 am

> more land left in a natural state where milkweed and other wild plants can flourish.

Not sure where you hail from but in agricultural Southern California the trend has been quite the opposite. Interstitial sites have been systematically repurposed for industrial agriculture.

Reply to  Rob_Dawg
December 27, 2018 3:29 pm

Not here in Indiana. I don’t think I’ve ever seen in my lifetime even a single acre ‘farmed’ that wasn’t already part of a field. WHAT went into each field might change based on market expectations and crop rotation plans, but no new fields were ever created out of fallow ground.

What has happened is just the opposite. New subdivisions keep expanding the suburbs outward, and in the country new homesteads keep cutting out an acre or five from formerly productive fields. And all that land looks like it’s going to be out of the farming circle for good.


December 27, 2018 10:39 am

I’ll try not to get too long winded with my post.
I have lived all of my 56 years in the same central Texas city (Temple, TX). It has grown from around 35,000 people when I was a teenager to around 75,000 people now. Yet it still takes only minutes to travel to rural areas outside the city limits.
Here are the land use changes I have noticed over these years. Much of the land near the city that used to be farms, ranches and fields are now covered with subdivisions. So all of the native plants have disappeared to be replaced with manicured green lawns.
Now expand on that process. Larger metropolitan areas, Dallas/Ft Worth, Houston, Austin, San Antonio cover large areas of land where native plants may be far and few between.

A couple of years ago I conversed via email with a professor that studies Monarchs. I had some questions regarding current building practices, more houses on smaller lots, more privacy fences, etc and whether this impeded Monarchs on their migration. The professor assured me this was no a problem as the Monarchs fly high enough.
What he said was a problem was large urban areas the Monarchs travel through on their migration. They are so large and offer so little food sources that the Monarchs have difficulty crossing them before they fatigue.

I can travel those few minutes to the rural areas outside Temple, TX and find milkweed, even along roads next to farms, where Roundup is said to kill milkweed due to spray drift. But I sure don’t find any milkweed in any of those manicured green lawns.

As for fewer California Monarchs making it to Mexico? Well those devastating wildfires caused by poor land management left vast areas of no food or water for migrating Monarchs.

M Courtney
December 27, 2018 10:40 am

So milkweed adapts to changes in CO2 concentration? Makes sense.
And the testing in a greenhouse proves it.

But Monarch Butterflies cannot adapt to changes in CO2 concentration? That makes no sense.
And there is no testing to prove it.

Evolution is real. These self-proclaimed entomologists should face that fact.

Curious George
December 27, 2018 10:45 am

Is anything today different from yesterday? THE END IS NIGH.

Fred Harwood
December 27, 2018 10:50 am

We had a substantial hatch and migration here in Western Massachusetts this year.

December 27, 2018 10:52 am

Monarchs have a thriving static population in the warm top-end of New Zealand. It’s possible to watch the entire life-cycle. Milkweeds are often grown in gardens, parks and cemeteries.
Monarchs can also be seen occasionally in the cooler South Island where they rely on swan plants instead of milkweed.

Reply to  Stephen
December 27, 2018 11:37 am

Just a minute . Monarchs in New Zealand. Monarchs in North America . Does that mean that they have survived since Australasia and the Americas were combined in a Gonwana- Laurasia supercontinent , about 200 million years ago?
Or is the term “Monarch” used indiscriminantly and actually refers to widely different genera .
I suppose they could have been introduced to NZ by travellors from America , perhaps inadvertently aboard a trading vessel .

Fred Harwood
Reply to  mikewaite
December 27, 2018 12:18 pm

Yes, they were introduced.

Maggy Wassilieff
Reply to  mikewaite
December 27, 2018 12:24 pm

They first arrived in NZ in 1870s..self-introduced.
They island-hopped across the Pacific and through S.E.Asia in the 1800s.
Either came across from Australia or down from New Caledonia.

December 27, 2018 10:55 am

Milkweed very common in the Sierras such as Yosemite Valley.

December 27, 2018 10:59 am

There are about 10 generations of Monarchs per year. That means 800 generations of adaption until 2100 CE. Now lets go back 800 generations of human adaption. Fringe survival, cave paintings in Spain, Neanderthals, Americas very likely unoccupied.

I’m thinking the butterflies will be fine. 200 million years times 10 generations per year of practice and they got it all over us “mayfly hoomins.”

Chris hagan
December 27, 2018 11:03 am

A more simple explanation is that with more CO2 in the atmosphere, their food sources(plants) are doing better and they are responding to more and better quality food?

But wait I forgot there are no positive effects of extra CO2.

Mickey Reno
December 27, 2018 11:07 am

Now wait just a damn minute. Farmers are killing off milkweed, the favored habitat of the migrating butterflies, and yet alleged CO2 based GHG warming is responsible for their decline? WTF? Are you authors (I won’t dignify you by calling you scientists) frackin’ (Battlestar Galactica reroll) insane?

Dr. Jim Steele, wet mess cleanup needed at National Geographic.

Mark Luhman
Reply to  Mickey Reno
December 28, 2018 5:27 pm

Milk weed was considered a noxious weed up to a short time ago. In a lot of places you were required to kill it.

December 27, 2018 11:15 am

My take is bio-fuels are responsible. Too much corn and pesticides. And that’s the heart of it.

December 27, 2018 11:16 am

And Nat. Geo’s nose is growing longer too because of….

December 27, 2018 11:28 am

” a monarch parasite with the tongue-twisting name Ophryocystis elektroscirrha. ”

…..and in a related paper

Ophryocystis elektroscirrha fails to thrive at CO2 450ppm…
…film at 11

Zig Zag Wanderer
December 27, 2018 11:29 am

Losing monarchs eh? Well that’s just careless. Heads of state should be better protected.

Australia managed to lose a prime minister once too, or was very embarrassing.

December 27, 2018 11:29 am

Growing up in Houston in the 80s and 90s, there were TONS of Monarchs every year. I’ve been back in Houston for 6 years and I don’t think I’ve seen one the entire time

December 27, 2018 11:29 am

“The monarch is the only butterfly known to make a two-way migration as birds do. …
Monarchs use a combination of air currents and thermals to travel long distances. Some fly as far as 3,000 miles to reach their winter home!”
Unless the air currents, at the time of migration always flow in the required direction, question is how they find their way there and back?
It is thought that some of migrating birds as well as homing pigeons may be using the earth’s magnetic field for navigation, so it may not be in the realm of a total fantasy to assume that the monarchs may have similar ability, which could be impaired by rapid changes in the intensity of magnetic filed.
This map
comment image
shows monarchs migration routes, while in this Link it can be seen the rapid acceleration (starting in the 1980s) in decline of the magnetic field intensity over the mid-west USA.

At this rate of the decline by 2050s the USA over-flying satellites will be exposed to dangerous levels of radiation (similar to the current South Atlantic anomaly area) having debilitating consequences for weather monitoring, hurricane tracking and the GPS navigation.

Reply to  vukcevic
December 27, 2018 11:35 am

Link showing the rapid acceleration in decline of the magnetic field intensity over the mid-west USA:

Reply to  vukcevic
December 27, 2018 12:57 pm

This magnetic reversal happens about every 200K years or so.

Reply to  MarkW
December 27, 2018 3:43 pm

We’re about due. It’s hard to judge because the cycle is pretty irregular. It’s also hard to judge because we aren’t sure how often the field collapses but reforms with the same orientation. The proxies we have only indicate the times it reforms reversed.


Reply to  Schitzree
December 28, 2018 9:06 am

The Earth’s MF field didn’t collapse during past reversals, magnetic poles just drifted across the equator on the, more or less, opposite sides of the globe.
If it did collapse the large proportion of the earth’s atmosphere would have been blown away by the solar wind during many reversals, and the most of the living organisms would have been killed off by the intense radiation.

Reply to  vukcevic
December 28, 2018 1:58 pm

Interesting. Where did you find that? What I remember reading was that the Earth’s magnetic field was supposed to break apart, possibly into as many as 6 much weaker dipoles, that wandered about independently until they reformed into a single dipole congruent to the pole of rotation. This new dipole could be orientated the same as the old one, or reversed.


TG McCoy
December 27, 2018 11:38 am

Alcohol based fuels are the problem-so to grow corn, you eliminate milkweed. The ethanol is used to reduce global temperature change? In doing so, you elimate Monarchs.
see! climate change IS the cause of the decline!
sort of..

Global Cooling
December 27, 2018 11:41 am

We’re losing sitting ducks fast Blame on them. They just sit, don’t fly away, just wait to be fed.

Why didn’t Darwin do his studies in a continent instead of a small island?

D Anderson
Reply to  Global Cooling
December 27, 2018 12:55 pm

I struggle to see the survival benefit of flying 4000 miles north and back every year. It actually takes several generations to make the trip.

Reply to  D Anderson
December 27, 2018 1:26 pm

Good question, maybe the struggle itself strengthens the species ?

Reply to  D Anderson
December 27, 2018 4:00 pm

Yes, it’s interesting. I believe it’s two generations that live a short time and the third that lives a much longer time to make the journey. Plus, they go to one place in Mexico and the study does not seem to have even mentioned changes there.

December 27, 2018 11:42 am

This is an example of why we have to WIN the “climate change” debate already. A species that used to be very common is now under threat of extinction. The real reason is primarily Monsanto’s poisoned crops, with other factors.

But screamers can get away with claiming ANYTHING is due to “climate change.” That distracts from handling the actual problems.

Reply to  ladylifegrows
December 27, 2018 4:20 pm

Monsanto’s poisoned crops

Damn it, where’s my Picard facepalm when I need it?

Oh, wait. Here it is.×432.jpg

Reply to  MarkW
December 27, 2018 4:42 pm

What’s that sound I hear? Is it WordPress laughing at us for thinking they wouldn’t let us down again? I think it is!


steve case
December 27, 2018 11:53 am

I was OK with a lot of what the article said but the part saying that Climate Change causes milkweed to produce a different mix of cardenolides, that is less effective against monarch parasites is a little too much to swallow.

December 27, 2018 11:53 am

“Rising CO2 levels from the burning of fossil fuels sit at the heart of climate change, …. .”

Link to proof, please?

No, thought not.

Reply to  Oldseadog
December 27, 2018 12:59 pm

Just more alarmist (might/possibly) hysteria

Crispin in Waterloo
December 27, 2018 12:05 pm

This is an interesting projection:

“But when Decker grew milkweed in a greenhouse with carbon dioxide levels of 760 parts per million (ppm)—what climate scientists project will happen in 150 to 200 years as the current level of 410 ppm continues to rise—she found that the plants produced a different mix of cardenolides, one that was less effective against monarch parasites. She published her findings in July 2018 in Ecology Letters.”

And where will the carbon come from to build up the atmosphere by 200 ppm above that is theoretically possible using all known fossil fuels plus 100%? That is quite a stretch.

There are two things wrong with this experiment – you could say omissions: she did not raise monarchs in that same environment to see if they already have epigenetic adaptations which would be invoked by the additional CO2 or by the physiology of the plant; she did not model the evolution necessary to adapt to the new conditions over 2 centuries. Perhaps they will adapt easily. The increased CO2 should lead to the eradication of the pest, based on all she told.

She is comparing the current insect and its current manifestations of epigenetic adaption with an extremely unlikely future condition. I don’t see how that is useful by itself.

There are monarch butterflies in Europe, Australia and New Zealand. They can fly across the Atlantic (and do). The normal wintering grounds are in Florida and Mexico, not so much California. The killing of their food base in the North through the use of herbicides is definitely impacting them. They used to have more food in the open pastures that were kept forest-free by humans who used fire extensively to manage the deer food supply (grasslands).

The banning of large scale use of fire as a management tool of course allowed the random regrowth of the forest (so-called second growth) with only the farmed fields kept open. So the solution it is really about maintaining habitat, not farming. Logging the new forests and burning the fields annually to keep them open – well you can guess how that will be received be ecologists who consider all actions of humans to be destructive. Nature, left to itself, would have the whole eastern half of N America covered in forests and there would be nearly no place for monarch butterflies at all. Fire managed by humans is part and parcel of the ecology of North America.

December 27, 2018 12:55 pm

“The invisible hand of fear and dread gripped Taylor’s gut.”

Wow, a two-fer!

Not only does Carrie get to cast real gloom and doom re the monarch she also gets to make an underhanded swat at Adam Smith’s “invisible hand” meme by associating the social benefits of individual actions (i.e. “the invisible hand”) with fear and dread.

kent beuchert
December 27, 2018 12:55 pm

Is therer any particular reason we should give a damn that yet another species becomes extinct because of environmental changes of some sort? I mean, how many species come into being and then leave ? Hundreds of thousands? Millions? Believe me, I won’t miss this particular butterfly. I wouldn’t know one if I saw one.

December 27, 2018 1:07 pm

All three images show butterflies on eucalypts non Californian natives perhaps they have already adapted.

Dudley Horscroft
Reply to  Gerard
December 29, 2018 11:47 pm

Exactly what I thought. Milkweed as known in the UK and Australia is a low growing weed – 6″ to 1′ at max, with a stem containing ample amounts of white sap which leaks out when the plant is broken or cut – hence “Milk” weed. What are they doing on Eucalypts? – unfortunately I cannot recognize which Eucalypt species those shown are. Perhaps it is the Eucalypts that are killing the Monarchs?

December 27, 2018 1:37 pm

There is probably a law in California requiring them to register. That is how they can be so precise.

Wiliam Haas
December 27, 2018 2:00 pm

The real problem is loss of habitat. The Monarch is the Milkweed Butterfly so destruction of Milkweed also results in destruction of the Milkweed Butterfly. I am now growing Milkweed in my garden and I have Monarch Butterflies as well as their caterpillars. They apparently have survived ice ages, the Holocene Optimum as well as the Eemian. Current climate change has been trivial as to what has happened over the last 600,000 years.

The reality is that the climate change we are experiencing today is caused by the sun and the oceans over which mankind has no control Despite the hype, there is no real evidence that CO2 has any effect on climate and plenty of scientific rationale to support the idea that the climate sensitivity of CO2 is zero. The climate change that we have been experiencing is so small that it takes networks of sophisticated sensors decades to even detect it. We must not confuse weather cycles with climate change. Mankind can provide more Milkweed for the Milkweed butterfly but we cannot affect the climate.

December 27, 2018 2:18 pm

Monarch butterflies are also found in Australia thanks to their migration. They like the warmth here. If the U.S. runs out of Monarchs, we can send a few breeding couples over to restart the population. They do not like harsh cold however. Temperatures below -8°C will kill about 50% of the monarchs as they freeze to death. Ice crystals that form on the butterfly can kill it. Also if the butterflies are wet, they do not like it either and it will kill close to 80-90% of the monarchs. Monarchs can’t fly unless they can warm their muscles to 55°F. They can’t even crawl below 41°F.

December 27, 2018 3:01 pm

I used to live in northern Oklahoma. The milkweed there grows, blooms, and goes to seed in the spring and early summer. After that, milkweed goes dormant. The monarchs I saw in the fall going south seemed to feed on wild asters and other plants. Their travels and feeding seemed to depend upon favorable winds going in the direction they were headed.

Steven F
Reply to  Rich LAMBERT
December 27, 2018 5:16 pm

The butterfly feeds on necter from flowering plants. Any flower with Necter will do. During the catapiller stage of life they eat the leaves of the milkweed plant. The adult butterflies only lay eggs on Milkweed.

December 27, 2018 3:04 pm

Monarch populations are in trouble — and very little is known with any degree of certainty about the causes. The intentional elimination of milkweed from the monarch’s breeding ranges is an obviously huge factor. – Nature has played a sorry trick on the monarch by limiting its larval (caterpillar) stage to a single plant host. It wasn’t really a bad ‘choice’ as milkweed is a prolific weed, producing huge numbers of seeds that are dispersed on the wind and readily take root in waste ground — like ditches and hiway verges. But now hiway verges are mowed just as milkweed flowers, ditches are kept cleared in many areas, and crops are maintained nearly weed-free.

It is blatantly FALSE that “climate change has forced the butterflies to travel longer distances as breeding grounds shift farther north.”

The monarch individuals that overwinter on the California Coast and in Mexico are not the monarchs that flew north from there in the spring. Monarchs are rather complicated: see Monarch Migration.

As a note, I have neighbors who visit roadside milkweeds Upstate New York and moved the eggs to milkweeds that they intentionally grow in their yard. They baby the plants until the young caterpillars enter the chrysalis stage. They then collect the chrysalises and protect them until the butterflies emerge a week or two later.

Reply to  Kip Hansen
December 27, 2018 4:03 pm

Years ago I started asking why many localities labelled milkweed as noxious weed. They were destroying the caterpillar’s feed source. I don’t think farmers have as much to do with this as do Weed and Pest districts. I have a patch of milkweed that I let grow in my yard for feed for the caterpillars.

Reply to  Kip Hansen
December 27, 2018 5:09 pm

Kip Hansen – you should do a post on this. The Nat Geo article is terrible and full of misinformation. Most people don’t seem to understand the difference between larval hosts (restricted to species in a few genera of what used to be the milkweed family [Asclepidaceae – now reduced to a subfamily in the Apocynaceae] – they do not depend on a single species of milkweed) and adult nectaring plants – Monarchs don’t need milkweed in autumn, they get their energy for migration from many different flowers. As you note with your link, they don’t start out in the spring and fly 3000 miles, but go through several generations that ‘breed’ their way north. California Monarchs stay pretty much in California although some crossing back and forth with other populations is suspected. The AGW ethanol scam making it profitable for farmers to plant maize on marginal land is probably as responsible or more so as Round-up ready plantings for reducing larval hosts – as well as urban sprawl. Global Warming would actually increase both the summer range and the overwintering area for Monarchs. They do fine here in Queensland (we usually call them Wanderers) and seem to have flown in on their own from New Caledonia to a heaven of milkweed weeds, cotton bush (Gomphocarpus spp. – I find Monarch caterpillars mostly on cotton bush), and some related vines and succulents that are fine larval food. And so on – you’d probably have a good time researching this and I would love to see what you find.

Crispin in Waterloo
Reply to  DaveW
December 27, 2018 5:20 pm


Good points. Monarch butterflies are or were major pollinators in N America before the introduction of honey bees from Europe. Yes, those bees that are supposedly being wiped out by climate change are non-native invaders we like. Like us.

The butterflies are flower drinkers without much preference.

Tasfay Martinov
December 27, 2018 3:15 pm

The default explanation which has become effectively the new null hypothesis is that “this too has been caused by anthropogenic global warming”.

But for this to be a scientific conjecture, rather than a chanted litany of faith, it has to be testable against an external null hypothesis that is different from the hypothesis being proposed.

How do we know, and test, that the population dynamics observed are not just the rather normal rapidly fluctuating quasi chaotic population dynamics of many or most living species within an ecosystem?

“It is easy to obtain confirmations, or verifications, for nearly every theory—if we look for confirmations. Confirmations should count only if they are the result of risky predictions… A theory which is not refutable by any conceivable event is non-scientific. Irrefutability is not a virtue of a theory (as people often think) but a vice. Every genuine test of a theory is an attempt to falsify it, or refute it.”

“In so far as a scientific statement speaks about reality, it must be falsifiable: and in so far as it is not falsifiable, it does not speak about reality.”

Karl Popper.

December 27, 2018 3:18 pm

I had two undergraduate mentors who were good scholars and teachers. Dr. Dale Birkland was a young ecologist, and I took his first ever course in ecology. He taught me a simple and understandable concept that species with highly restricted “niches” were always at risk (low ecological valence). The monarchs dependence on milkweed was one known example – way back in 1961. Dr. Ed Mockford was a new entomologist, with whom I worked for two years. He taught me one well-established principle for insects: they are very weather dependent and typically have boom and bust population years/cycles. Any given year the monarchs could boom or bust in any region of their breeding distribution, and counts in any given wintering area could change dramatically. When one puts there two long-established principles together, climate change doesn’t even have to enter the picture. I often wonder if our modern computer nimrods have had any basic training in established axioms of the sciences they practice.

December 27, 2018 3:59 pm

Note the warning, , Ïts not too late”, i.e. Keep the money coming for yet more research .

But lets go back to about 1980 and all of the warnings back then as to when it will be too late, and we are well past the date of our demise.

So lets stop worrying and live it up, as its “Now far too late”. Sarc of course.


December 27, 2018 5:05 pm

”But when Decker grew milkweed in a greenhouse with carbon dioxide levels of 760 parts per million (ppm)—what climate scientists project will happen in 150 to 200 years as the current level of 410 ppm continues to rise—she found that the plants produced a different mix of cardenolides, one that was less effective against monarch parasites. She published her findings in July 2018 in Ecology Letters”.

Ha ha ha ha ha. That’s a good one!

michael hart
December 27, 2018 5:28 pm

“We don’t know how we’re changing the green pharmacy around us,” Decker says.

She got one thing right then, but I could write a book about what she doesn’t know.

Hillbilly Joe
Reply to  michael hart
December 28, 2018 3:19 pm

The stupid continues to burn and would contribute to Gorbeal Warming if it actually existed.

Johann Wundersamer
December 28, 2018 12:48 am

scientists like Obserhauser say all is not yet lost –> Oberhauser

Jon O Beard
December 28, 2018 3:55 am

Let me get this straight, farmers used to allow milkweed to grow in between crops? An absurd assumption.

Reply to  Jon O Beard
December 28, 2018 9:36 am

Jon ==> Milkweed commonly grew in among crops in the MidWest — springing up after crops got too high to allow further mechanical weeding. With modern chemical weeding, there is almost no milkweed found in crop fields.

Elisa Berg
December 28, 2018 4:36 am

See this and other related sites ( This project is a couple of years old, and I don’t know it’s status.

December 28, 2018 6:03 am

Millions of then died a few years ago. They froze to death in Mexico.

December 28, 2018 6:53 am

Climate change? Stupid. Loss of Monarchs is from loss of trees in their small winter habitat-areas in Mexico. When almost all of them from N America are crowded into such tiny areas, they are obviously very vulnerable.

December 28, 2018 11:37 am

Articles like this on the monarch invariably and purposely ignore the massive wintering habitat destruction in Mexico. Since the 1999s 10 of the 13 known wintering sites were destroyed by local illegal logging. And the destruction continues… Ah but let’s rather talk about co2 in 100-200 years. Typical green response.

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