ESA Status: Under Review
The western bumble bee (Bombus occidentalis) used to be one of the most abundant bumble bees in North America. However, its population has experienced severe declines since the mid twentieth century. The U.S. Fish and Wildlife Service (USFWS) received a petition in 2015 to list the western bumble bee on the Endangered Species Act (ESA). The consequent 90-Day Finding, released in 2016, found the petition presented substantial scientific or commercial information, which indicated action may be warranted with further investigation.
Some of the main threats to the western bumble bee include pathogen transmission, insecticides, habitat loss and alteration from agricultural and urban development, fire suppression, grazing, logging, and climate change.