Blue Ridge Naturalist: Are Monarch Butterflies on Their Way to Extinction?

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© Marlene A. Condon

This Monarch feeding at Butterfly Bush (Buddleia sp.) blooms in the author’s yard was caught on camera a few years ago. As of the date this article was written, not one Monarch had made an appearance around the author’s home. Photo: Marlene A. Condon.
This Monarch feeding at Butterfly Bush (Buddleia sp.) blooms in the author’s yard was caught on camera a few years ago. As of the date this article was written, not one Monarch had made an appearance around the author’s home. Photo: Marlene A. Condon.

The abundance of rain this summer made for lovely surroundings that I’d practically forgotten were ever a possibility in central Virginia. Instead of looking parched and dry, the forests—both from a distance and up close—have been lush with growth. Herbaceous plants have also grown extremely well.

The world has looked so healthy, so capable of supporting all life. But something has been missing: Monarchs, the king of butterflies, have been nonexistent.

Not a one has visited my yard and none have been visible in Shenandoah National Park when I’ve given my monthly talks. On visits to various parts of the state, I have constantly kept my eyes open for these beautiful insects, but they have eluded me. This situation probably portends the future of the one insect that most people, including young children, can recognize.

2012 was not a good year for Monarchs, the orange-and-black butterflies that make the longest insect migration in the world. Each one weighs, on average, about half as much as a paper clip, yet it might fly as much as 2,500 miles (over 4,000 kilometers) to reach Mexico by November.

When scientists measured the overwintering acreage of these insects in Mexico in 2013 (they are unable to count individual butterflies), they found only about 2.74 acres (1.19 hectares) of land with Monarchs resting on the fir trees that shelter them from cold and wet conditions. This amounted to 59% less occupied acreage than in the previous year, which is statistically significant.

Consequently, this species of butterfly may be on its way to extinction. Indeed, there have been few reports of Monarch sightings across the Midwest and the East this year. When the population of any particular kind of critter gets quite small, that species is much more vulnerable to being wiped out should a catastrophic event occur.

According to a 2011 research paper by Sweetbriar College professor Lincoln P. Brower, et al., there are three factors implicated in the decreasing numbers of Monarchs.

(1) The downward trend began with the loss of critical overwintering habitat in Mexico due to extensive illegal logging. Fortunately, the destruction of the overwintering Oyamel Fir (Abies religiosa) forests has now come to a virtual halt.

(2) There’s been a widespread reduction of breeding habitat in the United States due to land development (6000 acres a day for 2.2 million acres a year), which means fewer milkweeds—the requisite food plant—for the Monarch caterpillar. Additionally, there’s been a loss of milkweeds as a result of the increased use of glyphosate herbicide (Round-up) to kill “weeds” growing in genetically engineered, herbicide-resistant crops.

(3) Periodic extreme weather conditions have decreased the spring breeding in Texas, which is the entry point to this country for Monarchs. Higher-than-normal temperatures decrease the lifespan of the butterflies, which reduces the number of eggs laid and thus results in fewer spring- and summer-breeding generations in the eastern United States and southern Canada.

Other scientists have pointed to the management of our roadsides as a factor in the decrease of Monarchs. Highway departments use herbicides and either excessive or untimely mowing, all of which decimate milkweeds as well as the caterpillars on them.

The obsession with manicured roadways to make them “more appealing” to travelers (as VDOT touted when they held a mowing blitz in advance of the July 4th holiday this year) is symptomatic of a culture out of touch with the serious consequences upon the environment of its actions.

Gardeners throughout the Midwest and the East could help Monarchs, but few want to plant the easiest milkweed to grow for these insects—the Common Milkweed (Asclepias syriaca). Tall and often ungainly in stature, it’s not the lovely specimen plant that gardeners concerned with aesthetics usually choose for their flower beds.

Instead they pick the Butterfly Weed (Asclepias tuberosa), a short plant with beautifully colored blooms of orange that stand out in the garden. Encouraged by virtually everyone—including some scientists who study Monarchs—to grow this plant, gardeners do a disservice to the Monarchs forced to lay their eggs upon Butterfly Weed.

Yes, these insects are forced to lay their eggs upon this particular milkweed when there are no other species nearby that are far better suited as food for their caterpillars. Unlike most milkweed species, Butterfly Weed is latex-poor and thus an inferior food plant for the Monarch caterpillar.

Latex contains the highly poisonous cardenolides that make the Monarch unpalatable to predators. These chemicals, concentrated in the abdomen and the wings of an adult where they don’t interfere with the butterfly’s metabolism, cause a nauseating taste in the mouths of predators, such as birds.

Butterfly Weed does not produce much of the cardenolides and thus confers less protection to the Monarch in both the immature and the adult phase. The result is undoubtedly an increase in Monarchs killed by predators, which must also be a factor in the continuing decline in the population of these regal butterflies.

A gardener can confirm for himself the inferior quality of Butterfly Weed by breaking a stem of this plant. The sap, rather than looking milky, as is the case with most milkweed plants and which is what gives them their name, is not at all milky. Instead it’s clear.

I first discovered this decades ago when I noticed that the Monarch butterflies never laid eggs on my Butterfly Weed. They always chose the Common Milkweed plants. The scientist in me wondered why and when I saw the difference in the sap, I surmised it must be of inferior quality. Further research confirmed my suspicion.

They say that ignorance is bliss, but ignorance can be deadly. That’s certainly been the case for our Monarchs as few people have chosen to plant the species of milkweeds that these butterflies prefer to utilize to increase their chances of surviving long enough to reproduce. And the highway department’s management of roadside growth, done without knowledge of or concern about its disastrous ecological impacts, is another case in point.

If you care about Monarchs, please grow Common Milkweed. In addition, please speak out against the excessive use of herbicides and mowing by the highway department. And last, but not least, please contact your Federal representatives to say they should support the Conservation Reserve Program (CRP).

This program pays farmers to set aside marginal land for wildlife that is not really well suited for growing crops anyway. Unfortunately, the funds allotted for the CRP have been cut drastically, yet this is one program where our tax dollars can be spent wisely. It helps all kinds of critters that help to keep the environment functioning properly so as to support mankind.

 

4 COMMENTS

  1. Awesome and accurate article describing the issues surrounding the devastating loss our monarchs have sustained in just the past few years. Each and every one of us can make a difference by simply planting a milkweed plant, even in a back corner of our property. Go to monarchwatch.org to get details on how to help this amazing creature!

    • While many of the things you say in your article are true, some things are not consistent with what is happening everywhere. I live in Kansas, in the middle of the country, and Monarch Butterflies (while not in as large numbers as the past) have been very present here this summer. In fact, each year I raise those who come to my milkweed and their numbers have increased this year over last year. Common milkweed is not native to the county in which I live, but there are other species of milkweed which attract the Monarchs beside Common Milkweed (Asclepias syriaca).and Butterfly weed (Asclepias tuberosa). We have prairie milkweed (Asclepias sullivanti), Swamp milkweed (Asclepias incarnata) and Showy Milkweed (Asclepias speciosa). I even grow the tropical milkweed (Asclepias curassivica). So, the fact that many people do not grow common milkweed does not mean that there are not others that can be just as important to Monarch Butterflies. Hopefully, those of us who try to influence people to grow milkweed, can help to bring back the Monarch population.
      If we decide that nothing can be done, then we become part of the problem.
      Thank you,
      Barbara Green
      3100 Harahey Ridge
      Manhattan, Kansas

      • To mybblucas,

        Thank you so VERY much for your kind and supportive words. I deeply appreciate it.

        To Barbara,

        Thank you for writing. Let me clarify why I wrote what I did.

        This article was for my local paper so I was writing to inform my local readers, not the entire country. I had not thought about the article being read online by folks from elsewhere.

        The reason I only mentioned Common Milkweed is because the article wasn’t really meant to be about gardening but rather about all of the problems Monarchs are facing in my state of Virginia. Space is always limited in a newspaper so I couldn’t possibly provide a listing as you did.

        Common Milkweed is native to most of the United States east of the Rocky Mountains which tells you it should be easy for anyone to grow in my immediate area or elsewhere in Virginia. That’s why I siimply recommended that particular plant.

        Sincerely,
        Marlene

        Marlene A. Condon
        Author/Photographer, The Nature-friendly Garden: Creating A Backyard Haven for Plants, Wildlife, and People (Stackpole Books)
        Naturalist and Writer/Photographer/Speaker
        Crozet, VA 22932-2204
        E-mail: [email protected]
        http://www.MARLENECONDON.com

        • thank you Marlene for your wonderful article on Monarchs. I, too noticed the absence of Monarchs last year on my property. I have lots of milkweed and have been trying to “rear” monarch caterpillars by taking them inside in November and giving them a chance to become beautiful butterflys. In previous years I found many caterpillars, but in 2013 I did not find a single one on our property. In 2012 I had 2 caterpillars form chrysalis in November. It was near freezing and windy with snow showers when they emerged. I kept them in my closet for 2 days in the dark in plastic totes. When I checked the weather forcast, it was still temps in 30’s. snow showers and windy. If i let them outside, they would die. If I kept them inside , they would die. So what did I do? My husband & I checked the local forcast for Lenoir, NC (piedmont) and their forecast was for 50 degrees and sunny the next day. We got up the next morning and transported the two monarchs about one hundred miles south. The sun came out, there was no snow and hardly any wind. I retreived the towel-covered tote boxes from the back seat. As soon as I removed the towel, the butterflies went straight to my window and fluttered against the sun-warmed glass. I rolled my window down, and out they went. Up into the sky flying south!!! I will never forget that day as long as I live. When we drove back up to Wilkesboro, NC and stopped for lunch. I noticed in the parking lot there were several monarchs on their way south….We returned to our home and the temps. were still in the 30’s and the snow was still flying. I will never regret giving those two Monarchs a chance to migrate to their winter home, hopefully to return again.

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