Roundup kills milkweed, the only host plant of the monarch butterfly. Citizen scientists have known for a few years now that the decline of milkweed is due to pesticide use which has depleted monarch populations in the Midwest where most of GMO corn and soy crop is planted now. What was once a diverse pollinator corridor has been reduced to remnant tallgrass prairie. Prairie has gone down by 90 percent in the USA.
Happy Tonics created a restored native tallgrass prairie, as a Monarch Butterfly Habitat, in Shell Lake, Wisconsin. We must do more. Gardeners need to plant milkweed to enable the monarch butterfly to rebound.