Rusty-patched bumble bee
Bombus affinis
Bee
A generalist bumble bee of the eastern and upper-midwestern United States, named for the rust-colored patch on the abdomen of workers and males. Like other bumble bees it performs buzz pollination, grabbing a flower's anthers and vibrating its flight muscles to release pollen that other pollinators cannot reach. As a short-tongued generalist it forages a broad sequence of native perennials across the colony's spring-through-fall flight, with documented Midwestern records concentrated on genera including Monarda, Agastache, Pycnanthemum, Eutrochium, Veronicastrum, and Solidago. Colonies nest underground, typically in abandoned rodent burrows.
Conservation
The first bee listed as Endangered under the U.S. Endangered Species Act (USFWS, January 2017), and assessed as Critically Endangered on the IUCN Red List. The Xerces Society, which petitioned for federal listing, treats it as critically imperiled. Abundance fell by roughly 87-92% from the 1990s to the 2010s, and the species is now largely restricted to the upper Midwest and parts of the Appalachians. Providing a continuous, pesticide-free succession of native bloom plus undisturbed nesting and overwintering ground are the canonical garden-scale conservation actions.
Plan for this species
Location-fit plant set for Chicago, IL: host and specialist plants first, then nectar, fruit, seed, foliage, and shelter plants that still fit the current and mid-century climate read.
0 essential relationships / 6 supporting plants
Host/specialist links: 0
Forage/pollination links: 6
Shelter links: 0
Relationship roles: 1
Anise hyssop
Supporting / Nectar plants
Aromatic aster
Supporting / Nectar plants
Dense blazing star
Supporting / Nectar plants
New England aster
Supporting / Nectar plants
New York ironweed
Supporting / Nectar plants
Purple coneflower
Supporting / Nectar plants
Plants in the catalog
Nectar plants · 12
Range
Historic range spanned the eastern United States from Maine south to Georgia and west through the upper Midwest to the Dakotas, north into Ontario and Quebec. It has been lost from the large majority of that range since the early 2000s and now persists mainly in the upper midwestern states and scattered Appalachian sites.
Sources & citations
Cite this page
Use this citation for the Plotwright wildlife record. Use the source cards below to explore the references that informed its taxonomy, range, conservation, host plants, foraging, and habitat.
Plotwright. (n.d.). Rusty-patched bumble bee (Bombus affinis). Retrieved 2026, August 20, from https://plotwright.com/wildlife/rusty-patched-bumblebee
Sources used for this record
This record is compiled from the sources below.
U.S. Fish & Wildlife Service: Rusty patched bumble bee
Federal species profile for ESA status, historical and current range, habitat needs, nesting, and broad nectar/pollen use.
Wikipedia: Bombus affinis
Corroborating reference for IUCN status, decline magnitude, historical range, and bumble-bee colony biology.
GBIF: Bombus affinis
GBIF backbone species Bombus affinis (Apidae) confirmed by an exact species-rank match on usageKey 1340481.
iNaturalist: Bombus affinis
iNaturalist species Bombus affinis, the rusty-patched bumble bee, with observation-backed distribution data.