Yet Another Fallout From GMOs: No More Monarch Butterflies?

This year, every siting of a Monarch butterfly – and indeed, butterflies in general, has been precious because there have been so few.

In fact, Monarchs are at their lowest population levels in decades and a major culprit is widespread planting of genetically modified crops (GMOs).  

How? Monarchs lay their eggs, and larvae feed on, only one plant called Milkweed (Asclepias). This ubiquitous plant  traditionally blanketed the Midwest – Monarch’s biggest reproductive grounds. Even turning much of the land to farming over the last couple hundred years didn’t impede the Monarch, because milkweed (and other wildflowers) still grew along edges and even between rows of corn and other crops. 

Milkweed on left; Butterfly Weed on right:

Monarch on MilkweedButterfly Weed

But in 1997, farming practices began to change and Monarch populations began to drop along with other pollinators, such as bees, which depend on native flowers.

That’s when Roundup-ready corn and soybeans entered the market. Since then, instead of tilling weeds, farmers spray entire fields with Roundup. And as insect resistance rises, they spray more and more.

Not surprisingly, this spraying kills every plant except Roundup-ready crops. No more milkweed means no more Monarchs and no more wildflowers means no more bees. But that’s not all – the spray itself kills butterflies and bees, and when they take nectar from GMO-plants, research on shows that harms them too by weakening their immune system.

Another change is that millions of acres of farmland used to be set aside as Conservation Reserve lands – the federal government paid farmers to leave the land to nature (a lesson learned from the Dust Bowl). But strong demand for corn-derived ethanol for biofuels now makes it more profitable for farmers to plant rather than preserve.

The US is losing what’s left of its prairies as a result.

"That habitat is virtually gone. We’ve lost well over 120 million acres, and probably closer to 150 million acres," Chip Taylor, director of Monarch Watch, told the NY Times.

And these crops aren’t only in the Midwest – Roundup-ready corn, soy and other GMO crops are planted in many areas of the US.

Climate Change Plays a Role

Recent weather patterns have also been hard on butterflies. Last year’s extreme heat and drought coupled with this spring’s lengthy cold and wet brought weather extremes butterflies can’t cope with.

Monarch’s ability to lay and hatch eggs is finely tuned to weather patterns that have been in place for thousands of years. But those patterns are changing now.

"Extreme climate fluctuations in the US and Canada affect the survival and reproduction of butterflies. Eggs, larvae and pupae develop more quickly in milder conditions. Temperatures above 95ºF can be lethal for larvae, and eggs dry out in hot, arid conditions, causing a drastic decrease in hatch rate," explains  Omar Vidal, Director of World Wildlife Fund-Mexico.
On the other hand, monarchs can’t fly and eggs don’t hatch if temperatures dip below 60ºF.

Wintering Grounds

During the winter, Monarchs hibernate at just one location in Mexico – a mountainous forest area where conditions are just right. They famously hang from the trees in enormous clusters of millions of butterflies – 350 million butterflies taking up as much as 52 acres. This past winter, only about 60 million monarchs covered a mere 3 acres of forest. 

Trees are literally covered with Monarchs:

Monarch wintering

Yet another threat to Monarchs has been logging in their wintering grounds and in 2000, Mexico set aside the area as a nature preserve.

Although the Mexican government has taken strong measures to protect the reserve from commercial logging, local impoverished residents continue small-scale illegal logging for firewood and building purposes, based on aerial photos.

"Communities must be paid more to compensate them for not cutting down trees and for protecting and reforesting the area," says Vidal.

Protect Pollinators

Like bees, butterflies provide essential pollinating functions for entire ecosystems. "The fruits, nuts, seeds and foliage that everything else feeds on," says Taylor. "If we pull the monarchs out of the system, we’re really pulling the rug out from under a whole lot of other species."

"This is one of the world’s great migrations." "To assure a future for monarchs, conservation and restoration of milkweeds needs to become a national priority," says Taylor.

If you are not familiar with the great Monarch migration, it’s worth learning about. It takes about four generations to make their awesome journey each year. Whether they come from the east or west coast of the US or from Canada, every Monarch ends up in Mexico in exactly the same spot to spend the winter, often on the very same tree from which their great-grandparents started out. 

"The monarch’s current situation is a striking example of the impact climate change can have on biodiversity. Extreme phenomena associated with climate change and the loss of natural habitat are increasingly common. Butterflies are usually "champions" of adaptation, making recent observations all the more troubling," says Montréal Space for Life and Insectarium.

Scientists still have hope that Monarch populations could rebound given better weather conditions and a strong move to protect and re-establish milkweed along their migration paths.

You Can Help 

Plants that attract Monarchs are easy to grow and require little watering: any plant in the milkweed family and butterfly weed (which are uniquely beautiful plants).

  • Simply choose a quiet location, sheltered from the wind and sun.
  • Look up "butterfly garden" or "monarch butterfly garden" to find their favorite native plants that bloom throughout the season. Do not buy plants at major retailers like Home Depot, which sell plants impregnated with pesticides.
  • Provide an area of wet sand near the flowers, where butterflies can drink, and a stone in the sun where they can rest.

In the spring, as milkweed emerges, a butterfly lays its eggs:

Monarch waystation

Learn more at Monarch Watch:

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Comments on “Yet Another Fallout From GMOs: No More Monarch Butterflies?”

  1. Kamia T.

    We’ve bought every type of Asclepias seed there is at some of the major seed retailers and planted them everywhere! I don’t always see monarchs frequenting them, but the bright oranges & pinks are pleasant, and I figure it can’t hurt.


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