The yellow-banded bumble bee (Bombus terricola) is a medium sized fuzzy bee with queens measuring about 20 mm and workers roughly 10 to 15 millimetres long. It is distinguished by its double-banded pattern of bright yellow on the second and third abdominal segments, and, commonly, a skirt of yellow hairs along the bottom of the fifth abdominal segment. They are most commonly seen in open areas adjacent to woodlands and wetlands, particularly in parks, gardens, suburban yards, and meadows where diverse wildflowers bloom throughout spring and summer. Males and females have the same basic colour pattern. The most obvious difference is their hairiness: males display distinctly longer, shaggier hair throughout their bodies, while females have short, neat, evenly-distributed hair.
The yellow-banded bumble bee follows an annual colony cycle beginning when a mated queen emerges from underground hibernation in spring and establishes a nest by laying eggs on a pollen-nectar mixture. Eggs hatch into larvae after about 5 days, then develop through four stages over 14 days before pupating for another 14 days and emerging as adult workers. Once the first workers emerge (about five weeks after the queen laid her first batch of eggs), they take over foraging and brood care while the queen focuses solely on laying eggs. By mid to late summer, the queen begins producing males and new queens, new queens receive more food and special pheromonal signals. Males emerge first, followed by new queens (also known as gynes). Gynes and males pair up to mate, then gynes go on to build up their fat stores and find a safe place in the leaf litter or underground to overwinter, entering diapause (a hibernation-like state) over the winter, emerging again the following spring to start their own colonies. Only newly-mated queens overwinter; all workers, males, and the founding queen die off as temperatures drop in fall.
In 2015, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessed the yellow-banded bumble bee as a species of Special Concern, and in 2018 they were added to Schedule 1 of the Species at Risk Act (SARA). Ontario officially designating the species as Special Concern the same year. Experts call for habitat restoration, continued surveys to track population size and distribution, and minimizing impacts from pesticides and commercial bees.
Since the 1990s, bumble bee numbers have been plummeting, and that spells ecological disaster. Ninety per cent of all flowering plants — including most of the fruits and vegetables in your fridge — need these pollinators in order to reproduce.
Until the causes of these declines can be reversed, conservation breeding and reintroduction is the only way to safeguard at-risk bumble bees. Today, WPC is the only organization in Canada rebuilding wild bumble bee populations through captive breeding. Thanks to recent breakthroughs, we’ve figured out how to dramatically increase the number of queens we produce. Once they’re released into the wild, they can establish their own colonies, producing hundreds of pollinators to sustain the ecosystems around them.
We work to prevent native bee species from disappearing by building self-sustaining populations in Canada, studying the various bee species to learn more about the threats they face, and create opportunities for community involvement.
In 2023 we plan to have:
Find out how Wildlife Preservation Canada is helping save native pollinators, including the yellow-banded bumble bee, and how you can make a difference.
Plant native flowers blooming from spring through fall, avoid pesticide use, and provide undisturbed ground where queens can nest. Leave some “messy” areas with logs, brush piles, and exposed soil. Report your sighting to Bumble Bee Watch (www.bumblebeewatch.org) every observation helps track population recovery and informs future conservation efforts.
Q: Why did the yellow-banded bumble bee species collapse so suddenly?
A: The decline wasn’t actually sudden—it was a catastrophic collapse across the subgenus Bombus sensu stricto starting in the mid-1990s, affecting multiple species simultaneously. The cause appears to involve a perfect storm of converging threats: the parasite Vairimorpha (formerly Nosema bombi) (possibly spread by escaped commercial bumblebees used in greenhouses), the introduction of neonicotinoid pesticides (highly toxic to bees), massive habitat loss from urbanization and agricultural intensification, and potentially climate change. The Rusty-Patched Bumble Bee, which shares this subgenus, has disappeared almost entirely; the Yellow-Banded has fared somewhat better, but still occupies only a fraction of its former range.
Q: How does bumble bee temperature regulation help or hurt them?
A: Their ability to generate heat and fly in cool conditions is actually a strength:, it allows them to forage in weather when other pollinators are inactive. However, this requires enormous energy expenditure. When food becomes scarce, stressed colonies can’t maintain the energy needed for this thermoregulation. Pesticides and parasites also impair their metabolic efficiency, making temperature regulation more costly and weakening their ability to survive poor conditions.
Q: Why is Vairimorpha bombi such a big threat?
A: This parasite is a unicellular fungus that infects the gut of bumble bees. Intense infections impair foraging ability, reduce immune function, and decrease reproductive success. The yellow-banded bumble bee suffers disproportionately high infection rates compared to stable bumble bee species. The parasite, though not invasive, was likely amplified through the transport of commercial bumble bee colonies. If not managed adequately, parasites, including Vairimorpha bombi, can spill over from commercial colonies into adjacent wild bee populations.
Q: What’s "buzz pollination" and why do bees do it?
A: Buzz pollination is a specialized technique where the bee grasps a flower’s pollen-producing structures in its jaws and vibrates its wing muscles at a specific frequency, causing the flower to literally shake loose pollen that would otherwise remain trapped in the flower’s anthers. Bumble bees, including the yellow-banded bumble bee, use this to access plants like tomatoes, peppers, potatoes, raspberries, and cranberries – some of which are impossible to pollinate without this behaviour. This makes them irreplaceable for certain crops, and is why there is a commercial bumble bee sector.
Q: Why do we need bumble bees when honeybees exist?
A: Bumble bees and honeybees are complementary pollinators with different foraging capabilities. Bumble bees can forage in cooler temperatures and lower light conditions than honeybees. They’re more effective pollinators of many native wildflowers, and they’re essential pollinators of major crops including tomatoes, blueberries, almonds, and cucumbers. Approximately 90% of flowering plants depend on animal pollinators, the loss of bumble bees threatens entire ecosystems, regardless of honeybee abundance. Honey bees are an agricultural species not native to North America and so are not in need of conservation action.
Q: How has the commercial bumble bee industry affected wild populations of bumble bees in general?
A: Commercial bumble bees (most commonly the common eastern bumble bee (Bombus impatiens)) used in greenhouse pollination can escape or become feral, spreading diseases and parasites to wild populations. Mismanagement of commercial bumble bees can also lead to their introduction outside of their native range.
Q: Why is captive breeding for insects so rare compared to vertebrates?
A: Insects have complex life cycles, specific temperature and humidity requirements, sensitivity to disturbance, and ecological specialization that make rearing difficult – especially so for eusocial insects like bumble bees. Unlike vertebrates, you can’t simply provide food and shelter, bumble bees need precise environmental conditions, specific pollen types, proper mating opportunities, and colony dynamics.
