[The Bees, Wasps, Hornets and Other Hymenoptera of the Columbia River Gorge of Oregon and Washington]

An unidentified bumble bee as observed on the flowers of gray rabbitbrush along the old railroad bed on the east bank of the Deschutes River about a mile upstream from the Columbia River, Deschutes River State Recreation Area.........November 12, 2017. Can you help identify the species of this bee?