While the numbers are still grim, this year’s annual monarch butterfly count at their winter home in the Mexican mountains showed a slight uptick from last year’s utterly dire record low.
Back in the mid-nineties, when yearly censuses of the Texas state insect began, the orange-and-black flying delights numbered more than one billion. By last winter, thanks to loss of summer habitat in the upper Midwest and other factors, their numbers were down by a staggering 966 million. While this year’s head count of 56.5 million was up by 22.5 million from that nadir, wildlife experts say that monarchs face an uncertain future, even if the species is not ready for endangered status just yet. (According to the World Wildlife Fund, its official status is “near threatened,” or “likely to become endangered in the near future.”)
Some of the monarch’s foes have been weather-related. That godawful Texas drought of 2011 and last year’s brutal, dragged-out winter did them no favors, and a freak freeze in their Michoacán overwintering grounds in 2002 left frozen monarch corpses knee-deep on the forest floor. (An estimated 250 million died in that winter storm.) Illegal logging of Michoacán timber once played a significant role as well, but by most accounts, the Mexican government has gotten that under control since 2010.
But the prime culprit is milkweed, or the lack thereof. Milkweed is the sole source of food for monarch caterpillars, and at one time, that seemed a fortuitous evolutionary strategy. After all, milkweed grows like a weed all over North America, so the young, bright-yellow, black-and-white monarch “cats” always had a feast at their many feet.
And then in the mid-nineties farmers in the Great Plains states—one of the monarch’s principal summering grounds—started planting genetically modified corn and soybeans, and then spraying their oceanic acreages of same with Roundup, a pesticide to which the crops were immune. Milkweed that once flourished amid the cornrows and along the verges of the fields perished by the megaton. That process accelerated in 2007, when Congress’s push for ethanol jacked up corn and soybean prices, causing farmers to plow and sow vast acreages of formerly milkweed-rich grasslands.
PolitiFact recently crunched some numbers. Quoting the journal Insect Conservation and Diversity, PolitiFact reported that between 1990 and 2010, the Midwest monarch population declined 81 percent, and Midwest milkweed declined by 58 percent over the same time period. Over roughly the same time frame, 94 percent of soybeans and 72 percent of corn had become genetically modified to be Roundup-resistant.
So, it’s all Monsanto’s fault, right?
Oregon Democratic representative Peter DeFazio certainly thinks so. In arguing that GMOs are toxic to nature, DeFazio claimed that “monarch butterflies are becoming extinct because of this sort of dumping, (the) huge increase in pesticides’ use because of these modified organisms.”
Maybe, or maybe not, according to PolitiFact. In labeling DeFazio’s statement a half-truth, they write:
DeFazio said that “monarch butterflies are becoming extinct” because of increased use of crops genetically modified to withstand pesticides.
The evidence of a connection is suggestive but not conclusive. Monarch populations have been declining alongside a shrinkage in its primary food source — milkweed — and the increased use of crops genetically modified to withstand pesticides and herbicides. However, causation has not been established yet, and other culprits — deforestation and unexpected weather events — are likely to have played a role as well.
Moreover, DeFazio exaggerated when he said that the butterfly species is “becoming extinct.” It faces significant challenges, but monarchs remain several steps away from extinction, and many conservationists think the trend can be mitigated.
That’s where you come in. At first blush, it seems simple: just throw down a few milkweed seeds in your yard, watch the flowering plants erupt from the ground, and delight in a garden flitting with monarchs.
It’s not that simple, sadly, as I know from personal experience.
In the fall of 2013, I noticed that our yard in Houston was still full of butterflies in late October, weeks after I understood they were supposed to have fluttered south. We had quite a bit of milkweed back there, so I just thought that these stragglers were tanking up for the last leg of their long journey. And then a few weeks later, I read for the first time about their horrible decline—which seemed odd to me, as my yard had recently been home to as many as fifteen at a time on occasion—and also that a milkweed shortage was to blame.
The solution seemed plain: plant beaucoup milkweed.
Around the same time we had our yard landscaped, and in full do-gooder mode, I asked that even more milkweed be planted. Today, there’s probably more milkweed back there than any other type of vegetation. And also today, here in mid-February, there are a few monarchs fluttering around out there, lazybones seduced by the plentitude of sweet, sweet nectar, so much so that they voted with their wings and decided not to make that hassle of a trip to Mexico at all.
Fine, I thought, maybe with global warming and all, they could safely winter on the Gulf Coast.
Wrong, according to a recent paper by University of Georgia monarch expert Dara Satterfield. It turns out my yard, and many like it, are full of the wrong kind of milkweed:
Concerned gardeners have started planting milkweed to help replace some of the butterflies’ lost breeding habitat. The most readily available commercially grown milkweed sold by garden centers is the exotic species Asclepias curassavica, or tropical milkweed. Monarchs love it, but, according to the study’s lead author Dara Satterfield, a doctoral student in the UGA Odum School of Ecology, tropical milkweed does not naturally die back in fall like perennial milkweeds native to North America. In fact, in parts of the southern U.S. from the Gulf Coast to the Atlantic, tropical milkweed can produce foliage and flowers year-round. This allows monarchs in those areas to stay put and keep breeding all winter.
And that’s how problems with disease arise.
It turns out that the monarchs in my backyard are very likely to be five times more susceptible to a debilitating parasite than their migratory cousins. Part of the function of the migration is to thin the cloud of infected butterflies, thus checking the parasite’s spread.
Our tropical milkweed-filled garden (pictured above) is a fool’s paradise, a sickly Shangri-la, like nineteenth-century New Orleans was for humans, where, as one British diplomat once put it, “a man may live well, but short.”
Fortunately, the situation is fairly easily remedied. The tropical milkweed needs to be hacked back to a height of about six inches every October, and maintained there throughout the winter, thus nudging the monarchs to be on their way. (Unless you live in the Valley; Satterfield says that leaving your tropical milkweed intact through the winter is okay in the extreme south of both Texas and Florida.)
Satterfield also recommends planting more strains of native perennial milkweeds to accompany the tropical variety. Ideally, you should phase out the non-native milkweed completely over time.
Which variety is right for you depends on where you are. Monarchwatch.org can give you the lowdown on which of the 73 varieties of milkweed are native to your county and the hookup on seeds and/or plants to boot.
(Photos by Wikipedia Commons)