Franklin's bumblebee (Bombus franklini) is known to be one of the most narrowly distributed bumblebee species, making it a critically endangered bee of the western United States. It is known only from a 190-by-70-mile (310 by 110 km) area in southern Oregon and northern California, between the Coast and Sierra-Cascade mountain ranges. It was last seen in 2006. Franklin's bumblebee is known to collect and nectar pollen from several wildflowers, such as lupine, California poppy, and horsemint, which causes it to be classified as a generalist forager.
Franklin's bumblebee is distinguished from other bumblebees by a solid black abdomen, with yellow anteriorly on the thorax in a U-shaped design. Females have black hair on their faces and the vertices, with some light hairs mixed above and below their antennal bases, while most similar bumblebee species have yellow. Males of this species are similar except their malar spaces are long and wide, the hair on males' faces is yellow, and tergum 6 has some pale hairs laterally.
The last sighting of this bumblebee species was in Oregon in 2006. Some sources say this species is already extinct, but until more concrete evidence is shown, it has been assigned a conservation status rank of G1, which is critically imperiled. Furthermore, the population decreased drastically since 1998.
- C. M. Pollock & C. Hilton-Taylor (2008). "Bombus franklini". IUCN Red List of Threatened Species. Version 2012.1. International Union for Conservation of Nature. Retrieved September 12, 2012.
- Williams, Paul H.; et al. (2012). "Unveiling cryptic species of the bumblebee subgenus Bombus s. str. worldwide with COI barcodes (Hymenoptera: Apidae)". Systematics and Biodiversity. 10 (1): 21–56. doi:10.1080/14772000.2012.664574.
- Jeff Barnard (24 June 2010). "Group seeks endangered listing for Franklin's bumblebee". USA Today. Retrieved 12 September 2012.
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- Bumble bees: Franklin’s bumble bee (Bombus franklini). Xerces Society.
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