The U.S. government is creating a safe place for bees in national wildlife refuges by phasing out the use of genetically modified crops and an agricultural pesticide implicated in the mass die-off of pollinators.

The U.S. Fish and Wildlife Service’s National Wildlife Refuge System manages 150 million acres across the country. By January 2016, the agency will ban the use of neonicotinoids, widely used nerve poisons that a growing number of scientific studies have shown are harmful to bees, birds, mammals, and fish. Neonicotinoids, also called neonics, can be sprayed on crops, but most often the seeds are coated with the pesticide so that the poison spreads throughout every part of the plant as it grows, including the pollen and nectar that pollinators such as bees and butterflies eat.

“We have determined that prophylactic use, such as a seed treatment, of the neonicotinoid pesticides that can distribute systemically in a plant and can affect a broad spectrum of non-target species is not consistent with Service policy,” James Kurth, chief of the National Wildlife Refuge System, wrote in a July 17 memo.

The move follows a regional wildlife chief’s decision on July 9 to ban neonics in Washington, Oregon, Idaho, Hawaii, and the Pacific Islands by 2016.

The nationwide ban, however, goes further, as it also prohibits the use of genetically modified seeds to grow crops to feed wildlife.

A FWS spokesperson declined to comment on why the agency was banning genetically modified organisms in wildlife refuges.

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But in his memo, Kurth cited existing agency policy. “We do not use genetically modified organisms in refuge management unless we determine their use is essential to accomplishing refuge purpose(s),” he wrote. “We have demonstrated our ability to successfully accomplish refuge purposes over the past two years without using genetically modified crops, therefore it is no longer [necessary] to say their use is essential to meet wildlife management objectives.”

GMOs have not been linked directly to the bee die-off. But the dominance of GMO crops has led to the widespread use of pesticides such as neonicotinoids and industrial farming practices that biologists believe are harming other pollinators, such as the monarch butterfly.

Neonicotinoids account for 40 percent of the global pesticide market and are used to treat most corn and soybean crops in the U.S.

“We are gratified that the Fish and Wildlife Service has finally concluded that industrial agriculture, with G.E. crops and powerful pesticides, is both bad for wildlife and inappropriate on refuge lands,” Jeff Ruch, executive director of Public Employees for Environmental Responsibility, said in a statement.