Speaking of Nature: Return of the monarch butterfly

  • The columnist found this beautiful monarch caterpillar on a milkweed plant in his back yard. It’s the first one he has seen in seven years. For The Recorder/Bill Danielson

  • This is one of the many monarch butterflies Bill Danielson has seen this summer. It is feeding on purple loosestrife flowers. For The Recorder/Bill Danielson

  • Bill Danielson

For The Recorder
Sunday, August 20, 2017

For many years now, I have managed a portion of my backyard as a monarch butterfly breeding ground. The area is the ground that lies atop the leach field. The soil is sand that was trucked in when the house was built, and it is of paramount importance that no trees be allowed to become established, lest they interfere with the proper function of the leach field.

Most leach fields I have seen are flat and green; covered with the beloved American lawn and cropped short and neat. My leach field, however, is a bit different. I make sure to mow it every year, but I allow a portion of the area to go un-mowed until the autumn. This way, the many interesting plants that like sandy soil are allowed to grow and bloom throughout the summer.

As it happens, one of the plants that really likes this situation is the common milkweed, the favored food plant of the monarch butterfly.

By leaving about half of the leach field untouched by the mower, I can usually get 20 to 30 milkweed plants to grow in a concentrated area. This has attracted many interesting insects, including monarch butterflies and the red milkweed beetles that I have written about in the past.

But for the past couple years, I have noticed an alarming lack of monarchs. In fact, when I went through my records, I discovered only one photo of a monarch in 2016 and none in 2014 or 2015. I had to go all the way back to 2013 to find a photo of a monarch butterfly, and all the way back to 2010 to find a photo of a monarch caterpillar.

One of the major factors contributing to the decline of monarch butterflies is the species favorite food source — the common milkweed. See that last bit on the end of the plant’s name? The “weed” part? Well that has caused a lot of problems.

Modern agriculture in the United States is heavily dependent on herbicides to maximize crop yields. One very clever human innovation has been to develop crop plants that are resistant to the glyphosate, which is an active ingredient in many herbicides (I won’t mention any by name). This means that fields filled with glyphosate-resistant plants can be slathered with herbicides.

From an agricultural standpoint, this might be a great thing, but it has had some devastating, unintended consequences.

Milkweed plants are included along with the other “weed” species that the herbicides kill. The use of herbicide-resistant crops meant that the application of herbicide could be broadened, which means that any plant other than the target crop is now obliterated. The end result is a huge swath of milkweed-free landscape for monarchs to attempt to traverse.

This is of special concern for monarch butterflies because of their natural history. It’s fairly well known that all of the world’s monarch butterflies spend the winter in a very tiny area down in Mexico. Adult butterflies eventually move northward in the spring, and they will eventually stop and lay eggs on milkweed plants. The adults then die and the next generation hatches, feeds, pupates, emerges as adults, flies north, lays some eggs and dies. This cycle is repeated several times before monarchs reach New England.

If at any point one of those generations hits a portion of the United States that has no milkweed plants, the entire species could go extinct.

Thus, huge swaths of the United States that have been rendered milkweed-free by the use of herbicides are dangerous to the extreme. I do not think for a moment that there is a single farmer in this country that is in favor of removing the monarch butterfly from the catalog of living species on this planet.

In fact, I imagine that the accidental removal of milkweed from the landscape was unforeseen by the people spraying the herbicides. The fact remains, however, that this “whoops-a-daisy” moment is a serious threat to a beloved symbol of summer, fall and nature, itself.

Let me end this on a positive note: in 2015, I saw only two monarch butterflies and in 2016, I only saw one. This summer, I have seen somewhere between 10 and 20 different individuals in several different locations. Most encouraging, however, is the fact that two weeks ago, while repeating what seemed like a more and more futile search with and ever-passing year, I found a big, beautiful monarch caterpillar on one of the milkweed plants growing on my leach field. This sudden burst of monarch activity has given me a wonderful feeling of optimism. I hope you see monarch butterflies in the coming weeks, and I hope that you, too, are filled with hope that we can fix this problem before it’s too late.

Bill Danielson has worked for the National Park Service, the U.S. Forest Service, and the Massachusetts State Parks. Visit www.speakingofnature.com for more information, or go to Speaking of Nature on Facebook.