Southern Plains Bumble Bee
As primarily a species of the eastern United States, this bumble bee is adapted to lower elevations, staying below 8,000 feet.
About This Species
While the Southern Plains bumble bee was never an abundant species, it is currently estimated to have declined by over 50%, occupying only 43% of its historic range. The Rocky Mountains mark the western edge of its range.
More Information:
Physical Characteristics
The Southern Plains bumble bee is a large bee that has uniformly short hair over its entire body, giving it a very tidy appearance. It has a fully black face and a mostly yellow thorax with a black oval connecting its wings across the middle. The first and second abdominal segments are typically yellow.
Range
The Southern Plains bumble bee is a predominantly eastern species. Colorado is at the western edge of its historic range.
Habitat
The primary habitat for this species is grasslands. However, rural and urban gardens also support this species.
Diet
Like all bumble bees, the Southern Plains bumble bee is a generalist, visiting a vast diversity of flowers, depending on what is available on the landscape. Milkweeds, Cassia trees, dalea flowers, blazing star flowers, sweet clovers, prairie coneflowers and goldenrods have been identified as some key food sources.
Reproduction
The Southern Plains bumble bee has a single annual cycle, which means it is born, matures, reproduces and dies within one year. Mated queens emerge in spring from their hibernacula, where they spend winter. (It’s thought that queens dig shallow holes in the ground to hibernate in.) After waking from hibernation, the queen seeks a suitable nest site, typically an old rodent burrow or natural cavity. She lays the first generation of eggs, forages nectar and pollen for the offspring, and raises them to adulthood. This first generation of daughters takes over the responsibilities of foraging and tending the next generation, leaving the queen to continue egg laying. After the first generation of daughters reach their adult stage, the queen never leaves the nest again. The colony grows throughout the season until the fall, when males and the next generation of queens emerge. These young queens forage to build up their fat reserves and mate prior to hibernation, preparing for the following spring. Once they find a suitable hibernation location, the queens settle down underground and enter diapause (insect hibernation) for the winter. They emerge in the spring and begin the cycle anew.
Threats to Species
Commercially managed bees (both bumble bees and European honey bees) pose a significant threat to native bumble bees. Managed bees can drive disease spillover, when a disease jumps from one population to another. Ongoing research demonstrates that honey bees can outcompete native bumble bees for resources and disrupt their natural foraging behavior. Pesticides also pose a threat to the western bumble bee, with both lethal and nonlethal consequences; bees can be exposed both directly through contact and indirectly through contaminated pollen, nectar and soil. Habitat loss is another major threat to the species, as they require healthy populations of flowers throughout the growing season and access to suitable nest sites. Finally, climate change poses a significant threat to the Southern Plains bumble bee in many ways, affecting the bees directly and indirectly through the ways their habitats will change.
Additional Information
There are a number of ways you can support this species: 1) plant native flowers incorporating species that bloom across the entire growing season, 2) avoid the use of pesticides (both herbicides and insecticides), and 3) participate in community science projects like iNaturalist or the Bumble Bee Atlas to help expand our understanding of species distribution and abundance.
If you would like to help CPW understand and protect our states bumble bees, you can participate in the Mountain States Bumble Bee Atlas. CPW is partnering with the Xerces Society for Invertebrate Conservation to get the Mountain States Atlas off the ground. Learn more here about how to get involved. If you are not able to participate in the Bumble Bee Atlas formally, you can submit photos of bumble bees you spot as one-off observations to the Bumble Bee Watch.