Rusty-Patched Bumble Bee

Bombus affinis
Species Status: Endangered in Canada; Critically Endangered globally (IUCN assessment)
Action Required: Conservation breeding and reintroduction

Rusty-Patched Bumble Bee (Bombus affinis)

One of the most common species of bumble bee in southern Ontario as recently as the 1980s, this hard-working pollinator is now on the brink of extinction throughout its large range. Despite thorough surveys of historic sites across Ontario, the rusty-patched bumble bee has not been observed in Canada since 2009.
The rusty-patched bumble bee gets its name from the rust-coloured patch found on the abdomens of workers and males. They also have distinctively short tongues. This means they occasionally “nectar-rob” flowers by piercing a hole through the back to access the nectar that their short tongues can’t reach. Spring queens emerge in early April, and the workers, males and new queens can live until late October, making it the species with the longest colony cycle in eastern North America.


The rusty-patched bumble bee is considered a habitat generalist, meaning that it can adapt to a wide range of environmental conditions. It forages from dozens of food plants, including milkweed, sunflowers, clovers and fruit blossoms. As recently as the early 1980s, it was seen quite commonly in the parks and ravines of the City of Toronto, as well as in urban gardens, wetlands and old fields and near forests. The last known location of rusty-patched bumble bees in Canada is in Ontario’s Pinery Provincial Park.


The rusty-patched bumble bee has a very large historical range along the east coast of the U.S. from southern Maine through Tennessee, with an extension west along the northern states through Minnesota. In Canada, it was found in southern Ontario and extreme southwestern Quebec. A study in southern Ontario in the early 1970s shows the rusty-patched bumble bee was then the fourth most common bumble bee species (out of 14).


Scientists have not pinpointed the reasons for the rapid decline of such a widespread and common pollinator. At the local level, pesticide use, habitat loss and increased competition with other species like the European honeybee contribute to declines. Range-wide factors may include climate change and infections carried by commercial bees.


Recommended Recovery Actions

The Ontario Recovery Strategy for rusty-patched bumble bee calls for a number of conservation measures, including restoring habitat, continuing to search for wild rusty-patched bumble bees at their historic sites and, if any queens can be located, establishing a conservation breeding program.

What we are doing

Find out how Wildlife Preservation Canada is helping save native pollinators, including bumble bees, and how you can make a difference.

We need your help

Donate to save endangered species
like the Rusty-Patched Bumble Bee