Rusty-patched bumble bees sighted – August 23, 2020

Rusty-patched bumble bee (Bombus affines) on Monarda. Photo Glenda Denniston

Glenda Denniston spotted the rare Rusty-patched bumble bee in the Preserve, and not just one but two individuals. She reported today: "Yesterday I photographed this Rusty-patched Bumble bee (B. affinis) on a Monarda near Second Oak, Frautschi. I sent the photos to Susan Carpenter, our local bee expert, and she confirmed the ID. Susan said it was a worker and that she was engaging in “nectar-robbing” behavior (bypassing pollination of the plant to access nectar by a shortcut). This is the first Rusty-patched I’ve seen in the Preserve in quite a while, though I haven’t been looking as carefully as I once did." One big reason Glenda spends much time in the area of the Second Oak at Frautschi Point is that she has been instrumental in developing the current flowering plant communities in this area, which attract many different pollinators.

See also an interview with Susan Carpenter, Friends member and leader of our popular pollinator field trips in the Preserve, about her research on Bombus affinis in the Arboretum, as well as her Guest Blog in the Scientific American on "How to protect our disappearing bumble bees."

The Rusty-patched bumble bee's tongue is not long enough to reach the nectary at the base of a tubular flower such as Monarda or wild bergamot. Thus it did some nectar thievery by perforating the flower petals at the base and gaining quick access through the hole to the food. Wild bergamot is a marvelous forage plant for bumble bees, especially those with long tongues. It keeps its flowers open all day, replenishes nectar continuously, and replaces spent flowers with new ones over much of the summer. The gallery below features two different individuals. Notice the darker brown spot on the B. affinis shown in the two lower photos. 

That same day, Glenda also spotted another bumble bee that is currently in the decline and of Special state concern in Wisconsin: the Yellow or Golden northern bumble bee (B. fervidus). see the photos below.