Scientists, wildlife conservationists, and food safety advocates have petitioned the U.S. Fish and Wildlife Service seeking Endangered Species Act protection for monarch butterflies (Danaus plexippus).

“Monarchs are in a deadly free fall and the threats they face are now so large in scale that Endangered Species Act protection is needed sooner rather than later, while there is still time to reverse the severe decline in the heart of their range,” Dr. Lincoln Brower, a monarch butterfly researcher and conservationist, and one of those seeking the Endangered Species designation. The Center for Biological Diversity and Center for Food Safety are serving as co-lead petitioners, joined by Brower the Xerces Society.

Brower and the petitioners believe Monarchs have declined by more than 90 percent in under 20 years. During the same period it is estimated that these iconic, and once-common, orange and black butterflies may have lost more than 165 million acres of habitat — an area about the size of Texas — including nearly a third of their summer breeding grounds.

“The monarch is the canary in the cornfield, a harbinger of environmental change that we’ve brought about on such a broad scale that many species of pollinators are now at risk if we don’t take action to protect them,” Brower said. He has been studying the species since 1954.

The petitioners say the butterfly’s dramatic decline is being driven by the widespread planting of genetically engineered crops in the Midwest, where most monarchs are born. The vast majority of genetically engineered crops are made to be resistant to Monsanto’s Roundup herbicide, a uniquely potent killer of milkweed, the monarch caterpillar’s only food. The dramatic surge in Roundup use with Roundup Ready crops has virtually wiped out milkweed plants in midwestern corn and soybean fields.

“The widespread decline of monarchs is driven by the massive spraying of herbicides on genetically engineered crops, which has virtually eliminated monarch habitat in cropland that dominates the Midwest landscape,” Bill Freese, a Center for Food Safety science policy analyst, siad in a statement to the press. “Doing what is needed to protect monarchs will also benefit pollinators and other valuable insects, and thus safeguard our food supply.”

Monarch butterflies are known for their spectacular multi-generational migration each year. Found throughout the United States during summer months, in winter most monarchs from east of the Rockies converge in the mountains of central Mexico, where they form tight clusters on just a few acres of trees. Most monarchs west of the Rockies migrate to trees along the California coast to overwinter.

The petitioners say the population has declined from a recorded high of approximately 1 billion butterflies in the mid-1990s to only 35 million butterflies last winter, the lowest number ever recorded. The overall population shows a steep and statistically significant decline of 90 percent over 20 years, they say. In addition to herbicide use with genetically engineered crops, monarchs are also threatened by global climate change, drought and heat waves, other pesticides, urban sprawl, and logging on their Mexican wintering grounds. Nearly half of the overwintering population in Mexico can be eaten by bird and mammal predators in any single winter; a single winter storm in 2002 killed an estimated 500 million monarchs — 14 times the size of the entire current population.

“We need to take immediate action to protect the monarch so that it doesn’t become another tragic example of a widespread species being erased because we falsely assumed it was too common to become extinct,” said Sarina Jepsen, endangered species director at the Xerces Society. “2014 marks the 100th anniversary of the extinction of the passenger pigeon, which was once so numerous no one would ever have believed it was at risk of extinction. History demonstrates that we cannot afford to be complacent about saving the monarch.”

The Fish and Wildlife Service is expected to issue a “90-day finding” on whether the petition, filed August 26th, warrants further review.

Photos provided by Wikimedia users. Above, a female monarch (Kenneth Dwain Harrelson); middle, a male monarch (Ram-Man); and below, overwintering monarchs cluster on oyamel trees in a preserve outside of Angangueo, Michoacan, Mexico (Bfpage).