Led by Mexican environmentalists, a campaign to plant a milkweed corridor to save the endangered Monarch butterfly is succeeding. The presidents of the US, Mexico and Canada agreed at last week's summit to create a task force overseeing the corridor currently threatened by pesticides and over-development. In a summit statement, the heads of state declared that "We will continue to collaborate in the protection of our region’s biodiversity and to address other environmental challenges, such as wildlife trafficking and ecosystems at risk. Our governments will establish a working group to ensure the conservation of the Monarch butterfly, a species that symbolizes our association." The environmental letter describes the urgent threat.