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Rusty-Patched Bumblebee

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The rusty-patched bumblebee is a newly listed endangered species in Canada and the first federally listed bee in North America. This species is on the brink of extinction throughout its large range. In Canada, only three individuals have been found in the past 10 years with the only currently known population occurring at Pinery Provincial Park.  This coming summer we will be searching suitable habitat and historical locations to locate other extant populations. We hope to locate populations where we can begin a captive breeding and re-release program which will be the first of its kind in North America.  Many bumblebees, including the rusty-patched bumblebee, are easily reared in captivity. This is why bumblebees are used globally to pollinate field and greenhouse crops. Once we establish good numbers of disease-free captive colonies, mated queens will be released in the fall to good quality habitat so they can overwinter and establish new colonies in the spring time.

Description

The rusty-patched bumblebee is named so because the workers and males have a distinct rusty patch surrounded by a yellow border on the second tergite (stripe) of their abdomen. The top stripe is solid yellow. The queens have two solid yellow stripes which is confusing because three other native bumblebee species also have the same colour pattern.  The rusty-patched bumblebee can be distinguished from them by its extremely short and dense hairs all over its body.  They also have very round faces and short tongues, which 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 persist until late October, making it the species with the longest colony cycle in eastern North America.

Rusty-Patched Bumblebee ID Guide

Bumblebee brochure

Habitat

The rusty-patched bumblebee is considered a habitat generalist.  As recently as the early 1980’s, it was seen quite commonly in the parks and ravines of the City of Toronto.  They have been collected in urban gardens, wetlands, old fields, and near forests.  Currently, the only known population occurs in a managed Oak Savannah remnant. The rust-patched bumblebee has been recorded as foraging from dozens of food plants, including milkweeds, sunflowers, clovers, berry and other fruit blossoms.

Distribution and Population Size

The rusty-patched bumblebee has a very large historical range along the east coast of the US from southern Maine through Tennessee with an extension west along the northern states through Minnesota.  In Canada, it is known to occur in southern Ontario and extreme southwestern Quebec. A study in southern Ontario documenting bumblebees in the early 1970’s shows the rusty-patched bumblebee was the 4th most common species (out of 14).  It has since become one of the rarest. A handful of individuals have been spotted in recent years from the Midwestern and Northeastern states but the species has completely vanished from the southern parts of its range, including Smoky Mountains National Park. A recent study country-wide survey estimated the rusty-patched bumblebee has declined throughout its US range by 86%. The species was assessed as Endangered federally (COSEWIC) and provincially (COSSARO) in 2010. It is not yet listed in the US.

Threats to Survival

The cause rapid decline of such a previously widespread and common pollinator still confuses scientists to this day. Threats known to cause decline of bumble bees at the local level include pesticide use, habitat loss and increased competition (e.g. with the European honey bee). Hypotheses as to the widespread decline of this species throughout its range include climate change and pathogen spillover from managed bees. The work WPC is undertaking will help scientists develop a better understanding of the threats to the rusty-patched bumblebee.

Species Recovery

This coming summer we will be searching suitable habitat and historical locations to locate populations where we can begin a captive breeding and re-release program which will be the first of its kind in North America.  Many bumblebees, including the rusty-patched bumblebee, are easily reared in captivity. This is why bumblebees are used globally to pollinate field and greenhouse crops. Once we establish good numbers of disease-free captive colonies, mated queens will be released in the fall to good quality habitat so they can overwinter and establish new colonies in the spring time.

What you can do to help.

Make a contribution today towards WPC.
Help reverse the loss of native pollinator habitat by protecting or planting native flowering plants on your property.
Let colonies of native bees exist on your property.  Although they can sting, bumblebees and other bees are quite docile when undisturbed and usually will only sting when trapped.
Support organic agriculture in Ontario.
Contact us (preferably with a digital photo) if you find a population of the rusty-patched bumblebee.

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