The data is in regarding the size of the monarch butterfly population in Mexico. The numbers were disappointing. As shown in the graph above, this year's population is nearly twice as large as last year's. That's a good thing, right?! Unfortunately, early data collected by Journey North at roosting sites along the migratory route made it appear that this year's numbers might more closely resemble those of 2011 - 2012. The actual population fell far short. Disappointing!
Obviously the monarch butterfly population is struggling and has been struggling for some time now. The question is, "What do we do about it?" The reason for the struggling population is complex, but most place a majority of the responsibility on Round-up Ready crops. Since 1996 for soybeans, and 1998 for corn, farmers have used Round-Up Ready crops. What this means is that the farmer can spray herbicide directly on the corn and soybeans with no ill effect on the crop.
This means that when the farmer sprays herbicide on his field, all that is killed is the weeds, including milkweed. Milkweed is the caterpillar host plant for the monarch. Therefore, as goes the milkweed so goes the butterfly. I suspect many of you can recall in your youth passing by corn fields and seeing milkweed grow at the edge. Many milkweeds are pioneer species, meaning they tend to colonize disturbed habitats. You don't get much more disturbed than an agricultural field. But thanks to herbicide-resistant crops, we no longer find milkweed at the edges of the fields.
Another challenge for the monarch butterfly can be found in America's obsession with mowing. We mow our highway right-of-ways several hundred feet from the edge of the pavement. We mow our county and township roadsides to look like putting greens. We mow our residential lawns twice a week, sometimes to the size of football fields. In Douglas Tallamy's book Bringing Nature Home, he estimates that in the United States the acreage that has been converted from "wild" to "lawn" would rival an area the size of the state of Illinois!
Once upon a time I lived in Indiana. I would tease people that I could drive a golf ball from Muncie to Richmond without going in the rough. I could do this not because I am a great golfer, but rather because there was no rough.
Between Round-Up and mowing, monarchs have lost a lot of milkweed. "But milkweed is invasive!" I have heard at several butterfly gardening classes I have taught. Let me take this opportunity to mention that native milkweed is NOT invasive. As a native, by definition, it cannot be invasive. It would be sort of like trying to claim that Native Americans are invasive in America. Doesn't make sense!
Some milkweeds, such as common milkweed (Asclepias syriaca, pictured above) do spread underground. This does not make it invasive. This makes it a pioneer species which can quickly colonize a disturbed site, sort of like tulip tree or black locust. The lawn in front of your house is far more worthy of the term invasive than milkweed.
Recently a group of people including the Xerces Society and scientist Lincoln Brower submitted a petition to the Fish and Wildlife Service to have the monarch declared as a threatened species. In State of the Monarch part 2 I will discuss this petition as well as other strategies to help bring the monarch population back.