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.