By Sylvia Fallon, Natural Resources Defense Council
The monarch butterfly population has declined yet again to 2.91 hectares—almost 30% less than last year’s population. The monarch population has been in steady decline for the past 20 years—reaching a high of over 20 hectares in 1997 and plunging to 0.67 hectares in 2014. Last year’s count indicated a hopeful increase to 4 hectares, but after a year that included a fatal winter storm that killed millions of monarchs, this year’s population is back down to one of its lower points.
In the meantime, the EPA has re-approved the registration for Dow’s Enlist Duo, a combination herbicide designed to kill milkweed, the monarch caterpillar’s only food source. Since the introduction of crops that are genetically engineered to resist herbicides (such as Round Up Ready crops), milkweed has been virtually eliminated from agricultural fields in the Midwest—an area that is a critical breeding ground for the monarch butterfly in the summer—thus contributing to the rapid decline in the population. Enlist Duo will continue to eliminate milkweed while increasing farmers’ dependency on toxic chemicals like glyphosate and 2, 4D for weed control creating a vicious pesticide treadmill.
Sustainable solutions for managing weeds exist including occasional crop rotation and increased crop diversity. In fact a recent study showed that having some milkweed present in corn fields actually helps attract beneficial insects that provide natural pest control thereby reducing the need for insecticides. These are the kinds of win-win solutions that we need to break the cycle of escalating pesticide use. Instead, however, EPA continues to approve more and more pesticides without fully considering the impacts of their use on human health and the environment—including, in this case, the impact to monarch butterflies.
Much effort has gone into planting milkweed throughout the continental US in the last several years in an attempt to make up for the milkweed that has been lost through agricultural practices. But this year’s monarch butterfly population demonstrates that we need to do much, much more if we are going to be successful at building the population back up again to secure numbers. Planting milkweed will not be enough. We also need to curb the use of pesticides that are eliminating milkweed in the first place and come up with sustainable solutions—not just for butterflies, but for farmers and our public health.