Rusty-patched Bumble Bee

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Not long ago, the Rusty- patched Bumblebee was among eastern North America’s most common Bombus species.

This docile bumblebee, whose workers and males are adorned with a single brightly colored abdominal patch, has been in serious decline for over a decade. Bombus affinis has likely been extirpated from Vermont and is absent in many parts of its former range. When we talk of pollinators in peril, this bumblebee defines the phrase.

Natural History

The Rusty-patched Bumblebee has a natural history similar to that of other bumble bees. The colonies are annual and initiated in early spring by a single queen. As spring progresses, the queen collects pollen and nectar, then secures a suitable nesting site to begin her colony, often in an abandoned rodent hole. Her first several broods consist solely of female workers who take over the collection of food, defense of the colony, and tend- ing to subsequent broods. Later in the summer, the queen begins producing males as well as next year’s queens. The males, whose sole purpose is to mate with new queens, provide neither resources nor defense for the colony.

By season’s end (late summer to early fall), the males die, as do the workers. The young queens, however, having mated and stored fertilized eggs, will enter diapause and survive the winter to begin a new colony the following spring.

The Decline

Historically, Rusty-patched Bumblebees ranged from Minnesota east to Maine and
as far south as Georgia. Recent surveys, however, show an extreme contraction of the species’ range with only isolated patches remaining in Midwestern and Northeastern states. Bombus affinis was last observed in Vermont in 1999.

The number of Rusty-patched Bumble Bees found by University of Vermont entomology students each decade.

The number of Rusty-patched Bumble Bees found by University of Vermont entomology students each decade.

Although the exact cause of this crash is uncertain, introduced parasites from imported colonies and pesticide use appear to be two major culprits. During the 1990s, to more successfully pollinate certain commercial crops, greenhouses across the United States began importing species of American bumblebees that had been reared in Europe. Having been exposed to foreign pathogens for which most native species had evolved no resistance, the imported bumblebees escaped the green- houses and infected bees in surrounding areas. In addi- tion, pesticides used to control other insect species also kill Bombus. Even small amounts used on lawns and in gardens can negatively impact entire colonies.

Conservation Action

Despite its dramatic decline, hope remains for the Rusty-patched Bumblebee. Both citizens and conservationists alike have taken notice of this pollinator’s decline and are working together to help this imperiled species.

Rusty-patched Bumble Bee News Archive

August 29, 2014

A Bumble Bee Vanishes

Almost every bumblebee you see this year will be dead before the year's end. That's normal. Bumble bees are burly — even brawny. But, with the exception of next year's queens, they are annuals. They end their lives with winter. What's not normal: The last living rusty-patched bumblebee — one of Vermont's more common species, once upon a time — was spotted in the Burlington Intervale on Aug. 31, 1999. To the untrained eye, the absence of Bombus affinis might pass unnoticed. more »

November 05, 2014

Bee Foraging Chronically Impaired by Pesticide Exposure

A study co-authored by a University of Guelph scientist that involved fitting bumblebees with tiny radio frequency tags shows long-term exposure to a neonicotinoid pesticide hampers bees’ ability to forage for pollen. more »

October 19, 2014

Citizen Scientist Makes Big Find

A trained entomologist living in White Post, Newhart, 61, was responsible for the collection of the rusty-patched bumblebee while surveying for the program at Sky Meadows State Park this summer. According to Jennifer Davis, outreach coordinator with Virginia Working Landscapes, the bumblebee was presumed to be extinct from the region. It had not been sighted in five years. more »

October 15, 2014

The buzz on the pollinator effect

For most people, the buzzing of bumblebees provides a low-level, throbbing anxiety. For growers, it should provide high-level excitement. Pollinators can greatly improve the quantity and quality of your yield. more »

December 03, 2013

Plight Of The Bumble Bee: Species In Decline

Vermont’s bumble bees are in trouble. A new investigation from the Vermont Center for Ecostudies has found that more than one quarter of the fuzzy bumbles have either vanished or are suffering a serious decline. more »