On Thursday, the International Union for Conservation of Nature added migratory monarch butterflies to its "Red List" of endangered species.
The monarch population in the U.S. and Canada has shrunk dramatically over the past decade. Their wintering areas in Mexico and California, and the milkweed their larvae feed upon, face threats from deforestation, pesticides, and climate change.
Eric Topper, director of education for Maine Audubon, says the monarchs that visit Maine from mid-summer through fall can use help from landowners.
"Grow milkweed, wherever you can," he says. "There are species that will play nicely in your garden and in your yard and won't take it over."
Topper says monarchs are really a back-to-school species in Maine, with peak abundance in early fall. So planting late-blooming native plants like asters and goldenrods will give the butterflies the nectar they need to fuel up for their return trip to Mexico.