The population in Mexico covered just 1.65 acres this winter, and that precipitous drop over the past 18 years has environmentalists increasingly worried about corn and soy that’s been genetically modified to withstand glyphosate, the herbicide Monsanto markets as Roundup, and the fate of a plant called milkweed. The weed is the only place where monarchs lay their eggs, and the near eradication of milkweed from agricultural land at the hands of glyphosate-spraying farmers is widely believed to be the reason for the plummeting butterfly numbers.
“Their precipitous loss signals a warning about the unintended consequences of our industrial agricultural practices,” Sylvia Fallon, senior scientist at NRDC, said in arelease. “We need to act quickly to ensure that future generations will also be able to experience the wonder of the monarch’s migration.”Now the Natural Resources Defense Council is petitioning the Environmental Protection Agency to review its rules for glyphosate use to save the monarchs.
A 2012 study published by The Royal Entomological Society’s Insect Conservation and Diversity journal found that the amount of milkweed growing in Iowa farm fields declined by 81 percent between 1999 and 2010.
“Given the established dominance of glyphosate-tolerant crop plants and widespread use of glyphosate herbicide, the virtual disappearance of milkweeds from agricultural fields is inevitable,” the study reads. With that loss of habitat, monarchs will never reach their previous numbers, and the authors point out that the new lower populations will be more vulnerable to extreme weather and deforestation at various points along their migration route.
Yet the decline in milkweed growing in Iowa’s woods and ditches and backyards was far less in the same time period: 31 percent over 11 years. It’s on such areas, where crops yields aren’t threatened by milkweed, that the NRDC petition is largely focused. The group is asking the EPA to block the use of herbicides along highways and power-line rights of way, to introduce glyphosate-free zones around farm fields, and to create other habitats where the plant can flourish.
Pulling apart milkweed pods and releasing the cotton-like fluff inside, setting the seeds floating off in the breeze, was just as much a part of my Iowa childhood as watching monarchs flit around the backyard. The corn and soy that dominate there and throughout the Midwest should be able to make way so that the butterflies and the plants that sustain them can remain a part of the landscape.