The rare Western Bumble Bee is easily reocgnized by the distinctive white patch on the rump (Nihuis 2013
). It was once one of the most common species of bumble bee in the Western US...but almost disappeared from a significant portion of its range (Nihuis 2013). Thorp (2013, pers. com) says "This species declined drastically in the western portions of its range from central California to southern BC over 10 years ago. It is just now beginning to show signs of recovery within scattered areas of its most severe decline, including the nearby Seattle area."