The first bumble bee species listed under the U.S. Endangered Species Act, with populations down 87% since the late 1990s.

Native status: Native to upper Midwest and eastern North America; federally endangered

§ Quick facts

SizeWorkers 9–13 mm; queens 17–22 mm
WeightWorkers ~90 mg; queens ~600 mg
LifespanWorkers 6 weeks; queens 1 year
OrderHymenoptera
FamilyApidae

§ Encyclopedia

Bombus affinis, commonly known as the rusty patched bumble bee, is a species of bumblebee endemic to North America. Its historical range in North America has been throughout the east and upper Midwest of the United States, north to Ontario, Canada, where it is considered a "species at risk", east to Quebec, south to Georgia, and west to the Dakotas. Its numbers have declined in 87% of its historical habitat range. In April 2010 it was assessed as Endangered in Canada, through the work of Sheila Colla and colleagues. On January 10, 2017, the United States Fish and Wildlife Service placed B. affinis on the list of endangered species, making the rusty patched bumble bee the first bee to be added to the list in the continental United States.

Source: Wikipedia — Bombus affinis Licensed under CC BY-SA 4.0

§ Identification

Field marks. Black body with reddish-orange "rusty patch" on the second abdominal segment. Yellow band across thorax.

Similar species. Other Bombus species (different patterns). Other rusty bee patches lack the band combination.

Voice. Buzz while flying and during pollen extraction.

§ Diet & behavior

Diet. Nectar (carbohydrate) and pollen (protein); both stored.

Behavior. Small annual colonies. Queens overwinter alone, found new colonies each spring. Critical pollinator of native plants. Federally endangered.

§ Range

Historically across upper Midwest and Northeast; now drastically reduced

§ Habitat

Grasslands, prairies, gardens with diverse native flowering plants

§ Threats

Pesticide exposure, habitat loss, disease spillover from commercial bumble bee colonies, climate change.

§ Conservation status

According to the IUCN Red List, the rusty patched bumble bee is currently classified as Critically Endangered.

§ What helps

Plant diverse native flowers. Stop pesticide use. Leave fall leaves to protect overwintering queens.

Support our work More ways to help

§ Further reading

§ Sources cited

  • Xerces Society
  • USFWS Recovery Plan
  • Bumble Bee Watch
  • IUCN Red List 2014