If I had a garden of my own, and didn’t live in urban squalor, I’d plant as many native milkweeds as I could: I find them a beautiful plant, plus I love the majesty of the Monarch Butterfly. Also yet another Monsanto product with devastating effects on our planet…
In recent years amateur conservationists have sought to replenish drastic declines in milkweed, the only plant female monarchs lay eggs on. But the most widely available milkweed for planting, the scientists say, is an exotic species called tropical milkweed — not the native species with which the butterflies evolved. That may lead to unseasonal breeding, putting monarchs at higher risk of disease and reproductive failure.
But in the Midwest, which produces half of Mexico’s wintering monarchs, the scores of wild milkweed species among grasslands and farms are fast disappearing.
Nearly 60 percent of native Midwestern milkweeds vanished between 1999 and 2009, the biologists Karen Oberhauser and John Pleasants reported in 2012 in the journal Insect Conservation and Diversity. The loss coincided with increased applications of the weedkiller Roundup on expanded plantings of corn and soybeans genetically altered to tolerate the herbicide. Meanwhile, monarch reproduction in the Midwest dropped more than 80 percent, as did populations in Mexico.
With the loss of native milkweeds that die in the fall, monarchs are encountering tropical milkweeds that are still thriving.
“There’s this huge groundswell of people planting tropical milkweed, and we don’t know what it’s doing to the butterflies,” said Francis X. Villablanca, a biology professor at California Polytechnic University. “We’re all in a rush to figure it out.”
Dr. Altizer fears that when monarchs encounter lush foliage in the fall, they may become confused, start breeding and stop migrating.
“It’s sad, because people think planting milkweed will help,” she said. “But when milkweed is available during the winter, it changes the butterfly’s behavior.”
Butterfly enthusiasts shouldn’t feel bad for planting tropical milkweed, monarch researchers say. But they should cut the plants back in fall and winter. Or even better, replace them with natives. There are native plant societies across the country that can offer advice.
(click here to continue reading For the Monarch Butterfly, a Long Road Back – NYTimes.com.)