Occurrences

Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.

Habitat

This species favors prairies and grasslands and is rarely associated with extensive forests. Considered a foraging generalist, this bumble bee will regularly visit floral resources in dunes, marshes, forest edges, farmland and urban areas.  Known foraging resources include milk-vetches (Astragalus spp.), thistles (Cirsium spp.), dogwoods (Cornus spp.), prairie-clovers (Dalea spp.), and sunflowers (Helianthus spp.), among other species (Wood et al. 2019). Nests are above ground among tufts of long grass, but occasionally occur underground in old rodent burrows. This species can also occupy agricultural landscapes, however associated pressures such as ground management and pesticides may restrict populations in these areas. Most Bombus queens overwinter in rotten wood or underground (COSEWIC 2010).

Natural Community Types

• Dry sand prairie
• Dry-mesic prairie
• Hillside prairie
• Lakeplain wet prairie
• Lakeplain wet-mesic prairie
• Mesic prairie
• Mesic sand prairie
• Prairie fen
• Southern wet meadow
• Wet prairie
• Wet-mesic prairie
• Wet-mesic sand prairie

Methodology

Management Recommendations

Common and widespread in its distribution prior to the late-1990s, this species, along with other species of bumble bees, has recently experienced declines throughout its historic range (Colla et al. 2012).  In Michigan, the range of B. pensylvanicus has decreased by approximately 98% compared to historic populations (Wood et al. 2019, Rowe et al. 2019). These losses are primarily attributed to three main threats: the widespread use on cropland since the early 1990s of neonicotinoids, a pesticide group highly toxic to bees,; both nesting and foraging habitat loss due to increased urbanization and agriculture, particularly the conversion of pasture to corn and soybeans; and the spread of pathogens from bumble bees used as pollinators in commercial greenhouse operations to wild populations nearby (Colla and Packer 2008, COSEWIC 2010, Grixti et al. 2009, Cameron et al. 2011). Conservation strategies for bumble bees center around preserving healthy natural habitat areas, reducing pesticide/herbicide use, and promoting native wildflower reestablishment within urban and agricultural landscapes. Additionally, planting hedgerows and restoring native grasses along field margins, and in urban parks and residential yards provides habitat for small mammals, whose abandoned holes may in turn become bumble bee nesting and hibernating habitat (Goulson 2010).

Active Period

Breeding from first week of September to first week of October

Flight from first week of July to fourth week of September

Nesting from fourth week of May to first week of July

Survey Methods

Surveys typically involve capturing foraging bumble bees with an aerial net and identifying the individual species (Colla and Packer 2008, Grixti et al. 2009). Observational or visual surveys are also common, and generally require two to three good photos for identification.

Aerial net, visual survey

Survey Period: From fourth week of May to first week of October

Time of Day: Daytime
Cloud Cover: Clear
Air Temperature: Above 60 degrees
Wind: No Wind

References

Survey References

• Colla, S.R. and L. Packer. 2008. Evidence for decline in eastern North American bumblebees (Hymenoptera: Apidae), with special focus on Bombus affinis Cresson. Biodiversity and Conservation 17: 1379-91.

• Grixti, J.C., L.T. Wong, S.A. Cameron and C. Favret. 2009. Decline of bumble bees (Bombus) in the North American Midwest. Biological Conservation 142: 75-84.

Technical References

• Cameron, S.A., J.D. Lozier, J.P. Strange, J.B. Koch, N. Cordes, L.F. Solter, and T.L. Griswold. 2011. Patterns of widespread decline in North American bumble bees. Proceedings of the National Academy of Sciences (USA) 108(2): 662-667.

• Colla, S.R. and L. Packer. 2008. Evidence for decline in eastern North American bumblebees (Hymenoptera: Apidae), with special focus on Bombus affinis Cresson. Biodiversity and Conservation 17: 1379-91.

• Colla, S.R., F. Gadallah, L. Richardson, D. Wagner, and L. Gall. 2012. Assessing declines of North American bumble bees (Bombus spp.) using museum specimens. Biodiversity and Conservation 21(14): 3585-3595.

• COSEWIC. 2010. COSEWIC assessment and status report on the Rusty-patched Bumble Bee Bombus affinis in Canada. Commitee on the Status of Endangered Wildlife in Canada. Ottawa. 34pp.

• Goulson, D. 2010. bumblebees: behavior, ecology and conservation. Second Edition. Oxford University Press, New York. 317pp.

• Grixti, J.C., L.T. Wong, S.A. Cameron and C. Favret. 2009. Decline of bumble bees (Bombus) in the North American Midwest. Biological Conservation 142: 75-84.

• Mitchell, T.B. 1962. Bees of the Eastern United States. North Carolina Agricultural Experiment Station Technical Bulletin No. 152.

• Rowe, L.M., D.L. Cuthrell, and H.D. Enander. 2019. Assessing Bumble Bee Diversity, Distribution, and Status for the Michigan Wildlife Action Plan. Michigan Natural Features Inventory, Report Number 2019-33, Lansing, USA.

• Williams, P.H., R.W. Thorp, L.L. Richardson, and S.R. Colla. 2014. Bumble bees of North America: an identification guide. Princeton University Press.

• Wood, T. J., J. Gibbs, K.K. Graham, and R. Isaacs. 2019. Narrow pollen diets are associated with declining Midwestern bumble bee species. Ecology, 100(6), e02697.