In 2019, the rusty patched bumble bee became Minnesota's state bee. Once common throughout the eastern United States and Midwest, its historic range has substantially contracted and now occurs in a small fraction of its former range. After The Xerces Society petitioned the U.S. Fish and Wildlife Service to list the species for protection under the Endangered Species Act, the Service formally listed the bee as federally endangered in January, 2017. To date, scattered rusty patched bumble bee populations still persist in Minnesota. 

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Bombus affinis is a short-tongued bumble bee species. Queens have a different coloration pattern than workers and males: Queens lack bright orange hairs on the base of the second tergite (T2) and have a distinct black dot on the top of the thorax. Workers have an upside-down T-shaped black marking on the thorax; males a broad black band between the wing bases. Queens, wokers and males have yellow hairs on the first and second tergites (T1 and T2) and the remaining tergites have black hairs. Males have scattered yellow hairs on the vertex (back of the head or "neck") and dark hairs on the face; queens and workers have dark hairs on the vertex and face. All castes have dark brown wings.