Agriculture giant Monsanto's signature herbicide has nearly eradicated the monarch butterfly, according to a Center for Food Safety study.

The study, released Thursday, found Monsanto’s herbicide glyphosate that is being sprayed on genetically engineered, herbicide-resistant corn and soybeans — known as Roundup Ready crops — are killing the monarch butterfly’s habitat and milkweed, the monarch caterpillar’s main food source.

Monsanto’s product, sold under the name Roundup, is unlike other weed killers in that is moves internally to the root tissue once its absorbed, not only killing but preventing regeneration of the milkweed.

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In less than 20 years, the Center for Food Safety said the monarch population has declined by 90 percent.

“This report is a wake-up call. This iconic species is on the verge of extinction because of Monsanto's Roundup Ready crop system,” Andrew Kimbrell, the executive director at the Center for Food Safety, said in a release.

“To let the monarch butterfly die out in order to allow Monsanto to sell its signature herbicide for a few more years is simply shameful.”

In a blog on its website, Monsanto said agricultural innovation has helped farmers grow crops more sustainably, but effectively controlling weeds in their fields does not prevent farmers from finding alternative places for monarchs to thrive.

“We are collaborating with experts from universities, nonprofits, and government agencies to help the monarch by restoring their habitat in Crop Reserve Program land, on-farm buffer strips, roadsides, utility rights-of way and government-owned land,” the company wrote.

On the heels of the report, the U.S. Fish and Wildlife Service said it would announce a new cooperative agreement and a new national fund to protect the monarch butterfly next week.

The cooperative agreement, according to a release, aims to “target the timely restoration of important monarch habitats across the country.”