Invertebrates
Rusty Patched Bumblebee
Bombus affinis · also called rusty patched bumblebees
Visiting one of the few remaining patches of suitable grassland within its former range, a rusty patched bumblebee forages for nectar, a species whose population has collapsed so severely that it became the first bee ever placed on the United States endangered species list.
Overview
The rusty patched bumblebee, Bombus affinis, is a social bee native to grassland and other open habitat across parts of the eastern and midwestern United States, now restricted to scattered remnant populations following a dramatic decline. Its status as the first bee species ever federally listed as endangered in the United States, catastrophic 90 percent population collapse, and vulnerability to a combination of disease, pesticides, and habitat loss make it one of the most conservation-significant native pollinators in North America.
A decline severe enough to make history
The rusty patched bumblebee’s collapse was steep enough to break new ground in US conservation policy, becoming the first bee species the country has ever formally recognised as endangered.
Status
Critically Endangered, having collapsed by an estimated 90 percent from historical numbers and disappeared from large parts of its former range.
Rusty Patched Bumblebee: common questions
Why was the rusty patched bumblebee the first bee listed as endangered in the United States?
This species experienced such a severe population collapse, an estimated 90 percent decline from historical numbers with disappearance from large parts of its former range, that federal wildlife officials determined it met the threshold for endangered species protection, making it the first bee species in the country's history to receive this designation.
What caused the rusty patched bumblebee's population to collapse?
This species has been affected by a combination of pressures, including pathogens spread from commercial bumblebee colonies used in agricultural pollination, pesticide exposure, habitat loss, and climate change, with researchers generally viewing this combination of factors, rather than any single cause, as responsible for the steep decline.
How can you identify a rusty patched bumblebee?
A worker or male of this species displays a small rust-coloured patch on the abdomen, a feature that gives the species its common name, though this identifying patch is notably absent in queens, meaning appearance alone does not always confirm identification across every member of a colony.
Where can the rusty patched bumblebee still be found?
This species is now restricted to scattered remnant populations within parts of its former range across the eastern and midwestern United States, a considerable contraction from the more widespread distribution it once maintained before its dramatic population collapse.