Recently, I worked with the Bumblebee Specialist Group to assess all 46 North American bumblebee species for the IUCN Red List. Bumblebees are among the best studied of our native bees so it made sense to start with them. Overall, one in four species were deemed to be at risk of extinction. Some species, like the critically endangered rusty-patched bumblebee (Bombus affinis), have exhibited rapid, wide-ranging declines, whereas others, like the American bumblebee (B. pensylvanicus) show long-term declining trends but are still present in good quality habitat. Some species remain common and have even expanded their ranges. This indicates that bees are not a monolith. Extinction risk varies by species and by region, as do the threats each species face. However, differences between species are often ignored by the media; it’s rare to go a week without seeing an article about catastrophic “bee” declines.
The rusty-patched bumblebee has not been seen in Canada since I last spotted it in 2009 at Pinery Provincial Park in southwestern Ontario. That day, I was driving around the park with a colleague and from the passenger seat noticed an unusual-looking bumblebee on the side of the road. I yelled at my colleague to stop the car and ran out to collect the bee with a vial. I put it on ice for a closer examination and confirmed it was in fact this exceedingly rare species. I’ve visited the park many times since without finding it again.
Museum collections tell us that a few decades ago, it was a generalist, commonly found in many types of habitats across southern Ontario and Quebec. It fed from hundreds of plant species. Its large queens would have been among the first to emerge in the spring, happily foraging on early blooming trees and shrubs. It also is among the last to wrap up, with males being spotted on goldenrod into September. It nests in rodent burrows and overwinters in rotting logs. Compared to other bumblebee species, its tongue is quite short. To get around this, it “nectar-robs” some plant species by piercing a hole at the base of the flower, a behaviour most other bumblebee species do not exhibit. In the 1970s, 14 out of every 100 bumblebees seen in southern Ontario would have been a member of this species. But its populations have collapsed throughout its large range, most likely because of an introduced disease and/or climate change. The story of the rusty-patched bumblebee is unique, as are the stories of all of our oft-neglected and declining native insect species. Their persistence relies on our appreciation of their uniqueness and using this information to design conservation plans.