Franklin's Bumble Bee is a predominately black bee with a distinctive yellow pattern on the front half of the thorax and two tufts of white hair on the tip of its abdomen. It has the smallest range of any bumble bee in the world; existing only in a small area in southern Oregon and northern California between the Coast and Sierra-Cascade mountain ranges. This bee is a generalist forager on many types of wildflowers, including lupines and California poppies. Since 1998, Franklin's Bumble Bee populations have drastically declined and the bee is on the brink of extinction.

IDENTIFICATION

In order to properly identify bumble bees, you need to first determine whether the bee you are examining is male or female. There are three different types of bumble bees you will encounter: workers, queens, and males. Both queens and workers are female. In most cases, queens and workers have similar coloration and physical features, except that queens are much larger. Males can differ in coloration from females of the same species, as well as other physical characteristics. Once you have determined the sex of your bee, you will want to identify whether it is Franklin's Bumble Bee or another species of bee.

Franklin's Bumble Bee can be easily distinguished from other bumble bees that are in its range by its distinctive pattern of yellow on the front of the thorax that extends rearward between and beyond the wing bases forming an inverted U-shape and its nearly completely black abdomen with two small white spots at the tip. Franklin's Bumble Bee females have a predominantly black face with yellow on top of the head; the males have mostly yellow on the front of their faces.

Within the historic range of Franklin's Bumble Bee, other black faced bumble bees that may be confused with B. franklini are the dark form of the Western Bumble Bee (Bombus occidentalis) and Fernald’s Cuckoo Bumble Bee (Bombus fernaldae). B. occidentalis and B. californicus females have black hair on the top of their heads in contrast to the yellow hair on B. franklini. B. californicus, B. occidentalis, and B. fernaldae have less extensive yellow on the front of the thorax which ends in front of the wing bases in contrast to B. franklini with its yellow extending rearward beyond the wing bases forming an inverted U-shape.  B. californicus and B. fernaldae also have a yellow band on the fourth abdominal segment. Females of B. californicus have a long face in contrast to the round face of B. franklini and B. occidentalis.  Additional bumble bees in the same area that look similar include: B. caliginosus, B. vandykei, B. vosnesenskii, and B. insularis.  These all have less extensive yellow on the thorax than B. franklini as described above.  They also have yellow on their faces and yellow on the fourth or third or fifth abdominal segments that is lacking in B. franklini. B. caliginosus, B. vandykei, B. vosnesenskii also have longer faces than B. franklini.

Franklin's Bumble Bee has the smallest range of any bumble bee in the world; historically its distribution could be covered by an oval approximately 190 miles from north to south and 70 miles from east to west in southern Oregon and northern California between the Coast and Sierra-Cascade mountain ranges. This bee has been found from low to high elevations (540-7800 feet). Populations of Franklin's Bumble Bee have declined precipitously since 1998; this bee is in imminent danger of extinction. Franklin's Bumble Bee was readily found throughout its range throughout the 1990s, but subsequent yearly surveys by Dr. Robbin Thorp have suggested this bee is nearly extinct. No Franklin’s Bumble Bees were observed during surveys in 2004, 2005 or 2007, and only a single worker was found in 2006.

The threats facing this species include: exotic diseases introduced via trafficking in commercial bumble bee queens and colonies for greenhouse pollination of tomatoes; habitat loss due to destruction, degradation, conversion; pesticides and pollution, inadequacy of current rules, regulations and law, and climate change affecting alpine habitat. Although Franklin's Bumble Bee is currently designated as a Species of Concern by the US Fish and Wildlife Service, this species has no substantive protection under federal law or Oregon or California state law.  

Please contact us if you have any information on the current or recent distribution of Bombus franklini. If you do research on bumble bees, have incidental bumble bees in your collection, or have student insect collections from the past few years, it would help us to know if you have or have not seen these bees. It is as important for us to document where these bees were formerly common, but not recently collected, as it is to document where they were collected.

View the status review for Bombus franklini on the Xerces Society's Red List of Pollinator Insects.

Much of the content for this page was developed from a petition, co-authored by professor emeritus Robbin Thorp (U.C. Davis Department of Entomology) and Scott Hoffman Black (Xerces). Bee illustrations were provided by Elaine Evans.

Funding for our efforts to conserve bumble bees in decline has been generously provided by the CS Fund and Xerces Society members.