GRANTS PASS, Ore. — Federal wildlife refuges in the Northwest and Hawaii will phase out a class of pesticides chemically similar to nicotine because they threaten bees and other pollinators key to crop growth.

The region covering Washington, Oregon, Idaho and Hawaii is the first in the agency to ban neonicotinoids. There is room for exemptions, but the goal is to phase out the pesticides by January 2016, U.S. Fish and Wildlife Service spokeswoman Miel Corbett said.

The agency’s pest-management policy calls for pest-killing methods that pose the least risk to wildlife, and there is scientific evidence that neonicotinoids kill bees and other pollinators, said Kim Trust, the agency’s deputy regional director of refuges.

“We made the decision because we are concerned over the global decline in all pollinators — bees and butterflies,” she said.

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Pollinators such as domestic honeybees and wild bumblebees and butterflies are vital to the proliferation of domestic crops as well as wild plants, spreading pollen that fertilizes the seed-producing flowers while they gather nectar. Their numbers have been declining worldwide.