Status: Special Concern in Canada since 2018 and in Ontario since 2016
Value to Property Owners and Ecosystems:
The Yellow-banded Bumble Bee emerges early in the spring, making it an important pollinator of early flowering species such as wild blueberry and apple crops. After spring these bees continue to provide significant pollination services which are essential to the growth of backyard gardens and healthy food crops. Without healthy pollinator populations, agricultural yields will decrease and global food shortages will quickly become a reality!
The yellow-banded bumble bee is a medium-sized bumble bee with a black head, short hair, and characteristically short tongue (it is shorter than most other bee species). Just behind their head, on their thorax, these bees have a yellow band followed by a large black band that extends to its abdomen (its wings are found in this black band). After the black band is a large yellow band (has two sections upon close inspection), followed by a smaller black band and a final small yellow section right at the end of its abdomen.
Diet: What do they eat?
Yellow-banded bumble bees feed on the nectar and pollen of a wide variety of plants. These bees emerge early in the spring meaning they require early flowering plants as well as others that bloom throughout their active season in order to have a constant food sources
Habitat and Range:
Yellow-banded bumble bees are habitat generalists as they are found in a wide variety of meadows, grasslands, wetlands, forests, urban areas, boreal habitats and farms. They generally nest and overwinter in mixed woodland habitats, nesting in abandoned rodent burrows, and overwintering underground in decaying organic matter.
Currently, the yellow-banded bumble bee has a typical range stretching from the Yukon boreal forest down into southern Ontario, and the northeast and northern portions of the midwest United States. The historic range of this once common bumble bee spanned across Canada; however, since 2003, populations in the southern part of its Canadian range have declined by at least 34%.
Biology and Life Cycle:
Mated queens emerge in the early spring to find and establish a nest location and then proceed to lay their eggs. In late summer, males and new queens leave the nest to mate. Mated queens overwinter, but the rest (males, old queen, and workers) die at the end of the season.
Threats: Why are they a Species At Risk?
Pathogen spillover: The introduction of diseases from domestic or managed bee populations used for agricultural purposes is believed to be a significant contributing factor to the population declines of the yellow-banded bumble bee. One of these pathogens is the fungus Nosema bombi which effects the gut health of bees.
Pesticides: Yellow-banded bumble bees can be directly exposed to a variety of lethal pesticides, including particularly harmful neonicotinoids while foraging. They can also be indirectly exposed to pesticides while feeding on contaminated pollen or nectar.
Habitat loss, fragmentation and degradation: Although the yellow-banded bumble bee does not have specific habitat requirements however, it does require mating, foraging, nesting and overwintering habitat all within a relatively close range of each other. Human development has contributed to habitat degradation and fragmentation which separates these habitats from each other and makes it harder for yellow-banded's populations to stay established.
Climate change: Bees have been found to be emerging 10 days earlier than 100 years ago as a result of the warmer temperatures associated with climate change. As such, there is an increased potential for mismatch of pollinators and food sources (i.e. flowers may start to bloom too late or too early for bees) and of queens emerging before winter is truly over (because of continued climatic variation).
Current Conservation Efforts:
Researchers are working diligently to try and restore healthy populations of yellow-banded bumble bees. Below are some examples of what they are doing.
- Breeding programs: Researchers are collecting wild queens that emerge in the summer and are providing them with the ideal habitat conditions to promote successful colonies. When winter comes researchers collect the next generation of healthy queens and house them somewhere safe until their release to carefully selected locations.
- Community science programs: By engaging the public in scientific research (volunteers report any species sightings of bees using online applications), academics are able to gain vast amounts of valuable information that would regularly be impossible due to limited resources. One such program is the Bumble Bee Watch!
How can you help the Yellow-Banded Bumble Bee?
1. Learn how to identify them and report any sightings: With the help of this guide, learn how to identify Yellow-banded Bumble Bees and submit observations to The Land Between online and/or to iNaturalist. Your observations help scientists monitor and track Yellow-banded Bumble Bee populations!
2. Plant native wildflowers in your garden: Plant a pollinator-friendly garden with a variety of native flowers that bloom from early spring to late fall so that pollinators have a food source throughout their entire life cycle!
3. Do not kill dandelions in spring/Practice no mow May: Yellow-banded bumble bee queens feed on dandelion flowers in early spring when they emerge from their overwintering sites, as they are one of the only sources of food available at that time. Consider leaving the dandelions on your property (not removing or mowing them) until after other flowers are in bloom so bees have as much access to food as possible.
4. Leave rodent burrows intact: Consider leaving old rodent burrows on your property intact. These burrows can be used as nests by the yellow-banded bumble bee, and other bee species. In exchange for your hospitality, the bees will provide you with pollinating services for your garden
5. Do not rake and remove leaves in the fall or spring: Yellow-banded bumble bees over winter under organic matter and organic debris like leaves (a layer of leaves helps provide insulation from the cold)! Allow your leaves to stay on your lawn for the winter and only rake and remove them if you must in the spring once temperatures are consistently above 10°C
FUN FACT: The Yellow-Banded Bumble Bee is capable of shivering in order to warm itself to its minimum required body temperature of approximately 30 degrees Celsius! It can even do this during cooler temperatures which makes them a relatively cold-tolerant species!
- McIvor, C. A., & Malone, L. A. (1995). Nosema bombi, a microsporidian pathogen of the bumble bee Bombus terrestris (L.). New Zealand Journal of Zoology, 22(1), 25-31.
Goodell, K., Mitchell, R., & Lanterman, J. (2019). Distribution and Habitat Use of the Rusty Patched Bumble Bee (Bombus affinis) and the Yellow-Banded Bumble Bee (Bombus terricola) in Ohio (No. FHWA/OH-2019-25).
Dominey, K. A. (2021). Are Yellow-banded Bumble Bee (YBBB) Bombus terricola and Gypsy Cuckoo Bumble Bee (GCBB) Bombus bohemicus at risk in Cape Breton?.