The monarch butterfly’s serious decline
By Frances LambertsThe late opinion editor of the Johnson City Press would have been saddened by news in mid-March of steep population decline in our best known butterfly.
Tom Hodge often wrote about the monarch butterfly, calling it “my special pet because of the amazing migration the monarch takes.”
Monarchs breeding east of the Rocky Mountains, more numerous than the western population, fly 3,000 miles in fall to spend the winter in a high-altitude forest in Mexico.
There, they cluster on trees by the millions, in a Biosphere-Reserve area set aside by the Mexican government.
The Monarch Watch organization’s report in March was alarming. Ever fewer butterflies make it to the wintering grounds. In the latter half of the ’90s, wintering monarchs covered sanctuary trees on more than 26 acres. Between 1999-2003, tree area they occupied averaged less than 20 acres, during the 2004-2008 winters 12 acres.
Since then, total tree area occupied was barely six acres and last winter’s monarch population, covering less than three acres, was the lowest ever observed.
Hodge had worried about logging in the Mexican forest affecting the survival of his “pets.” But their chief peril now may lie, not in destruction of the wintering grounds but in lack of their food sources in our own country.
As early as 1999, the Union of Concerned Scientists warned that genetically engineered crops, in wide use on industrial agriculture farms, were making a “Bitter Harvest” for butterflies.
Engineered to produce an insect poison as they grow, the pollen from “transgenic” corn dusting milkweed plants in fields was a particular threat to monarchs.
Studies at Cornell University and elsewhere had found 50 percent mortality among caterpillars feeding on such milkweed, and any survivors growing poorly.
Since nearly half the eastern monarchs move through the cornbelt during their annual migrations, large numbers of offspring become incidental victims of modern-day agriculture.
Other crops have been engineered to grow successfully despite intensive herbicide application that kills unwanted (non-crop) plants.
The wide utilization of these herbicide-tolerant crops, Monarch Watch states in its analysis of causes of the great monarch decline, “has all but eliminated milkweeds from [the] fields.”
It notes that the loss, since 2006 alone, of more than 25 million acres “of milkweed-containing Conservation Reserve Program land” to corn and soybeans for biofuel adds to the monarch’s food-scarcity problem. Edge to field-edge intensive farming, roadside management with herbicides and “development which consumes 6,000 acres a day” all cause continual shrinkage of nectar and caterpillar food sources for all butterflies.
The only “good-news” item in the sobering new statistics on monarch survival is that their extreme food loss can be reversed through the planting of “lots and lots of milkweed.”
The recommendation would have had Hodge’s hearty support.
In an article before his death he wrote that “if everyone who lives in a house in this nation could dedicate one square yard of his lawn to milkweed plants,” this butterfly’s habitat would be restored and the monarch population boom again.