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Endangered Species Program
Conserving and restoring threatened and endangered species and their ecosystems
Rusty Patched Bumble Bee
Bee Identification: Is it a rusty patched bumble bee?
If you think you have seen a rusty patched bumble bee, please try to take photographs (photos from the top, side, and head are helpful; see Bee Photography Tips) and upload to bumblebeewatch, beespotter.org and/or bumblebee brigade. Experts will provide or verify identifications, if it's possible, from the photos.
There 21 species of bumble bees in the eastern United States and 48 species in the entire U.S. If you think you have observed a rusty patched bumble bee, below is information to help you with your identification. At the bottom of this page are links to helpful bumble bee identification guides. For more details about how to identify the rusty patched bumble bee, see these guides and Appendix C in our Survey Protocols for Rusty Patched Bumble Bee.
Standard insect anatomy terms are used to describe bees for identification. Follow this link to the Xerces Society page that illustrates bumble bee anatomy for identification purposes: https://www.bumblebeewatch.org/anatomy/
Queens, Workers and Males
All rusty patched bumble bees have a mostly yellow upper thorax with a black spot or band between the wings that may extend toward the back in a v-shape.
The bottom of the thorax is black (not shown on this illustration).
Workers and Males
In workers and males, the first abdominal segment is yellow, and the second has a a patch of rusty hairs on the front portion of the segment, with yellow hairs on the back and sides.
Workers can be seen in the field several weeks after nest establishment, throughout the summer, into early fall (late June-September). Males are in flight in late summer and fall (August-September).
Rusty patched bumble bee queens are entirely yellow on the first two abdominal segments and the rest of the abdominal segments are black.
The timing for observing queens depends on your geographical location. For example, in southern Wisconsin, queens, distinguished by larger size and other characteristics described above, are in flight in spring (roughly mid March - May) and then again in late summer and fall.
In this photo of a rusty patched bumble bee, the yellow thorax with a black spot between the wings that extends toward the back, can be seen.
The rusty patch, which is an area of rust-colored hairs, is on the front of the second abdominal segment with yellow hairs on the sides and towards the back of the segment.
Can Be Confused With
Rusty patched bumble bees can be confused with the: brown-belted bumble bee (Bombus griseocollis), half-black bumble bee (B. vagans), lemon cuckoo bumble bee (B. citrinus), and confusing bumble bee (B. perplexus).
Brown-belted Bumble Bee
Rusty patched bumble bees are most commonly confused with brown-belted bumble bees.
The second abdominal segment of the brown belted bumble bee has brown hairs towards the front and black hairs on the sides and back.
The brown-belted bumble bee is common in the eastern United States.
Last updated: August 17, 2018