(Reuters) - The U.S. Fish and Wildlife Service on Wednesday proposed listing the rusty patched bumble bee, a prized but vanishing pollinator once widely found in the upper Midwest and Northeastern United States, for federal protection as an endangered species. 
 
 A rusty patched bumble bee which the U.S. Fish and Wildlife Service proposed listing for federal protection as an endangered species is pictured in Madison, Wisconsin, U.S. August 7, 2015. Photo courtesy of Rich Hatfield/Handout via REUTERS 
 
 One of several wild bee species seen declining over the past two decades, the rusty patched bumble bee is the first in the continental United States formally proposed for listing under the U.S. Endangered Species Act. 
 
 Named for the conspicuous reddish blotch on its abdomen, the rusty patched bumble bee — or Bombus affinis, as it is known to scientists — has plunged in abundance and distribution by more than 90 percent since the late 1990s, according to the Fish and Wildlife Service. 
 
 The agency attributes the decline to a number of factors, including disease, pesticides, climate change and habitat loss. 
 
 Bumble bees, as distinguished from domesticated honey bees, are essential pollinators of wildflowers and about a third of U.S. crops, from blueberries to tomatoes, said Sarina Jepsen of the Xerces Society for Invertebrate Conservation, which petitioned the government for protection of the insect. 
 
 Bumble bees’ annual economic value to farms is estimated at $3.5 billion, according to experts. 
 
 The rusty patched species is one of 47 varieties of native bumble bees in the United States and Canada, more than a quarter of which face a risk of extinction, according to the International Union for the Conservation of Nature. 
 
 Population declines among wild bees are much more difficult to document than those in honey bees, which are for the most part managed commercially and whose numbers are carefully tracked by beekeepers, Jespen said. 
 
 Jepsen said protections proposed for the rusty patched bumble bee will intensify the debate over the degree to which so-called neonicotinoid pesticides, routinely used in agriculture and applied to plants and trees in gardens and parks, have contributed to the decline of native bees. 
 
 “Endangered Species Act safeguards are now the only way the bumble bee would have a fighting chance for survival,” she added. 
 
 The Fish and Wildlife Service last year proposed protections for seven types of yellow-faced, or masked bees, in Hawaii. 
 
 The public comment period initiated by Wednesday’s proposed listing runs through Nov. 21, 2016, after which the agency could revise its proposal or finalize a decision. 

 "As pollinators, rusty patched bumblebees contribute to our food security and the healthy functioning of our ecosystems," the Fish and Wildlife Service said in a statement. The federal agency estimates that native insect species, particularly bees, contribute $3 billion in economic value annually in the United States. Because of a specialized pollen-shedding movement called "buzz pollination," bumblebee species are better at pollinating some crops than honeybees.
– The rusty patched bumblebee has gone from a widespread and well-known pollinator to the edge of extinction in just 20 years. Reuters reports that the species, which got its name from the reddish patch on its abdomen, has been proposed for the endangered species list by the US Fish and Wildlife Service. It would be the first of the US and Canada's 47 bumblebee species on the list. The bee's population has dropped by close to 90% since the late 1990s because of factors including disease and habitat loss, according to Fish and Wildlife, which describes this species and other bumblebees as pollinators that "contribute to our food security and the healthy functioning of our ecosystems." Rusty patched bumblebees were once found in at least 26 eastern states, but they're only seen in a handful of states today, according to the Xerces Society for Invertebrate Conservation, which asked the government to safeguard the species. The Los Angeles Times notes that the bee's decline is bad news for anybody who eats food: It has a longer life span than most bumblebees and is better than most at pollinating crops, including cranberries, plums, alfalfa, and apples. (Spraying for Zika mosquitoes in South Carolina ended up killing millions of honeybees.)