Better living through chemistry is turning out to be really untrue, especially for species that live in the wild. Humans are making a mess of their habitats in a lot of ways, and one of them is with the use of chemicals to increase crop yields.
Pesticides serve the purpose of killing off the bugs that devour and ruin crops, but at the same time, they also can kill off insects that are beneficial to life on earth, like bees. Herbicides can and do the food various species need to survive, like the Monarch Butterfly.
In recent years, the numbers of Monarch Butterflies spotting during their migration to and from Mexico every year has declined 80% in the last two decades. The blame for this is being laid at an herbicide called dicamba which is sprayed on genetically modified crops developed to resist it. Dicamba, it turns out, also kills milkweed which is the only food the caterpillars that eventually become Monarch butterflies eat. Hence, when the milkweed along the migration path is destroyed, no Monarch butterflies will cocoon and develop.
As described in an analysis I released earlier this month, peer-reviewed research shows that just 1 percent of the minimum recommended dicamba application rate can drastically reduce the size of milkweed and severely wither the leaves the caterpillars need to survive.
Dicamba may even cause greater harm to milkweed than the pesticide glyphosate, which has played a significant role in reducing milkweed across the heart of the monarch’s annual migratory path.
Worse yet, as demonstrated by an interactive mapping tool on the Center for Biological Diversity’s website, the timing and geographical distribution of dicamba use coincides precisely with the presence of monarch eggs and larva on milkweed.
Milkweed is an invasive plant that will grow on fences (this yard has had it for decades), so purposefully planting it is not the best idea in the garden. However, providing a haven of butterfly-friendly flowers can be helpful. Black-eyed Susans, Petunias, Pansies, and Dahlias are among the flowers that will attract butterflies.