Franklin's bumble bees need a sufficient supply of nectar and pollen throughout the colony season. They use a variety of flowering plants, including lupine, California poppy, horsemint, and penny-royal. These bees require abandoned rodent borrows or clumps of grass for nesting.
Limiting factors
Franklin's bumble bees are vulnerable to habitat loss and alteration. Fire suppression contributes to loss of meadow habitat. Disease, pesticide applications, potential competition with honey bees for floral resources, and climate change present additional threats.
Data gaps
Monitor historical sites. Obtain population estimates. Evaluate pathology and control of Nosema bombi [Microsporidia] and other potential disease organisms (such as Locustacrus buchneri [Acarina] and Crithidia bombi [Protozoa]). Determine susceptibility of commercially-reared and wild bumble bee species to pathogens.
Conservation actions
Since this species has not been seen since 2006, surveys that target historical sites are needed. If B. franklini is found, protect important bumble bee habitat.
