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Montana Field Guides

Common Eastern Bumble Bee - Bombus impatiens
Other Names:  Pyrobombus impatiens

Non-native Species

Global Rank: G5
State Rank: SNA

Agency Status


External Links

General Description
For definitions and diagrams of bumble bee morphology please see the Montana State Entomology Collection's Bumble Bee Morphology page. A medium-tongued large bee: queen 21-23 mm, worker 9-14 mm. Hair short and even; head length medium with as long as broad or just shorter than broad; mid-leg basitarsus back far corner rounded, outer surface of hind-leg tibia flat and without long hair but with long fringes at sided forming a pollen basket; hair of the face black or with a few yellow hairs; thorax mostly yellow, with a large patch between the wings intermixed with black hairs; T1 yellow, T2 usually entirely black, T3-6 black. Male 12-14 mm; eye similar in size to any female bumble bee; antennae medium length with flagelum 3X longer than scape; hair color similar to queens and workers, but with a yellow patch below the antennae and many yellow hairs on underside of segments 2-6 of abdomen (Colla et al. 2011, Williams et al. 2014).

Emerges in early spring. Queens active April to October, workers May to November, males June to November (Colla et al. 2011, Williams et al. 2014). In southern Ontario, the earliest record 23 April, queens active April to October, workers May to October, males June to October (Colla and Dumesh 2010); in the Boston Massachusetts area, queens emerge from hibernacula starting 15 April, workers appear in early June, the majority of young queens and males in August and September (Plath 1934).

Diagnostic Characteristics
Please see the Montana State Entomology Collection's Key to Female Bumble Bees in Montana. Females distinguished from other Montana Bombus by a combination of concave and shiny outer surface of hind-leg tibia with pollen basket present; cheek slightly longer than wide; T1 yellow, T2-6 black; scutellum yellow only or intermixed with black throughout.

Species Range
Resident Year Round

Recorded Montana Distribution

Click the map for additional distribution information.
Distributional Information Provided in Collaboration with the
Montana Entomology Collection at Montana State University


Range Comments
In the East from southern Canada to the Gulf of Mexico and west to the Great Plains. Widespread and abundant, possibly expanding its range to the northeast (Colla and Packer 2008, Grixti et al. 2009, Cameron et al. 2011, Williams et al. 2014). Only a few records for Montana, which might represent inadvertent introductions, as this species is commonly released in greenhouses for pollination of crops.

In or near woodlands, grasslands, farmlands, wetlands, urban parks and gardens (Matteson and Langellotto 2009, Colla and Dumesh 2010, Williams et al. 2014). Also uses tallgrass prairie patches in the upper Midwest (Hines and Hendrix 2005).

Food Habits
Recorded from more than 75 species of flowers, including Agastache, Amelanchier, Aquilegia, Arabis, Arctium, Asclepias, Berberis, Bidens, Camassia, Campanula, Caragana, Carduus, Ceanothus, Centaurea, Cicuta, Cirsium, Claytonia, Clematis, Collinsia, Coreopsis, Crataegus, Dalea, Daucus, Delphinium, Echinacea, Echium, Epilobium, Erythronium, Eupatorium, Fragaria, Gaura, Geranium, Helenium, Helianthus, Hesperis, Hydrophyllum, Hypericum, Impatiens, Kalmia, Lactuca, Liatris, Lithospermum, Lonicera, Lupinus, Lycopus, Lythrum, Malus, Medicago, Melilotus, Mentha, Monarda, Nepeta, Oenothera, Onopordum, Osmorhiza, Pediomelum, Penstemon, Philadelphus, Phlox, Polemonium, Potentilla, Prenanthes, Prunella, Prunus, Rhododendron, Rhus, Ribes, Rosa, Rubus, Rudbeckia, Salix, Salvia, Scrophularia, Scutellaria, Silene, Solanum, Solidago, Spiraea, Stachys, Symphoricarpos, Symphyotrichum, Symphytum, Taraxacum, Trifolium, Vaccinium, Verbena, Vicia and Viola (Plath 1934, Macior 1968, MacKenzie and Averill 1995, Stubbs and Drummond 2001, Ratti et al. 2008, Colla and Dumesh 2010, Colla et al. 2011, Williams et al. 2014, Tripoldi and Szalanski 2015). Used to pollinate commercial blueberry (Vaccinium) field crops as well as a variety of greenhouse vegetables, such as tomatoes, muskmelons, and sweet peppers (Stubbs and Drummond 2001, Matteson and Langellotto 2009).

Reproductive Characteristics
Nests underground. Plath (1934) reported 80 nests during the years 1921-1933, all of which were subterranean, located at depths of 30-90 cm, and with entrance tunnels extending 45-271 cm. In southern Ontario queens dig hibernacula from late September through October at depths of 3 to 15 cm, sometimes hibernating as pairs, more often singly; spring emergence occurred from early April throughout May, with peak emergence in late April (Szabo and Pengelly 1973). Nest are quite large, with one Massachusetts nest in early August containing 1 dead queen, 450 workers, and a large quantity of brood, which included at least 500 male and queen cocoons (Plath 1934); an Ontario nest excavated in late October contained 16 queens and a brood comb containing 1357 small cocoons and 674 larger cocoons (Szabo and Pengelly 1973). Number of queens and males per colony can be relatively small (mean for each in 11 captive colonies = 9, range: 0-69), but colonies contain a large number of workers (mean in 11 colonies = 375, range: 186-540)(Cnaani et al. 2002).

Eggs of all castes produce larvae in 5 days, queens remain as larve for about 18 days, 9-10 days for workers and males; the pupal stage lasts about 14 days for queens, 10-11 days for workers and males. Workers are capable of laying eggs and rearing larvae to adulthood in colonies that are two months old (Cnaani et al. 2002). Worker size can vary ten-fold, with smaller workers better able to resist starvation, which may help colonies persist through times of nectar shortage (Couvillon and Dornhaus2010). Nests are parasitized by the cuckoo bumble bee Bombus citrinus; 14.3% of 49 nests in the Boston area were parasitized by this species (Plath 1934, Colla et al. 2011, Williams et al. 2014). However, experimental evidence shows that B. impatiens is probably a secondary host for B. citrinus, given the relatively low success rate of invading nests of this host species compared to the primary host, B. vagans (Fisher 1985).

  • Literature Cited AboveLegend:   View Online Publication
    • 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 108(2): 662-667.
    • Cnaani, J., R. Schmid-Hempel, and J.O. Schmidt. 2002. Colony development, larval development and worker reproduction in Bombus impatiens Cresson. Insectes Sociaux 49:164-170.
    • Colla, S., L. Richardson, and P. Williams. 2011. Bumble bees of the eastern United States. Washington, DC: USDA Forest Service, Pollinator Partnership. 103 p.
    • Colla, S.R. and L. Packer. 2008. Evidence for decline in eastern North American bumble bees (Hymenoptera: Apidae), with special focus on Bombus affinis Cresson. Biodiversity Conservation 17: 1379-1391.
    • Colla, S.R. and S. Dumesh. 2010. The bumble bees of southern Ontario: notes on natural history and distribution. Journal of the Entomological Society of Ontario 141:39-68.
    • Couvillon, M.J. and A. Dornhaus. 2010. Small worker bumble bees (Bombus impatiens) are hardier against starvation than their larger sisters. Insectes Sociaux 57:193-197.
    • Fisher, R.M. 1985. Evolution and host specificity: dichotomous invarion success of Psithyrus citrinus (Hymenoptera: Apidae), a bumblebee social parasite in colonies of its two hosts. Canadian journal of Zoology 63:977-981.
    • 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.
    • Hines, H.M. and S.D. Hendrix. 2005. Bumble bee (Hymenoptera: Apidae) diversity and abundance in tallgrass priaire patches: effects of local and landscape floral resources. Environmental Entomology 34(6): 1477-1484.
    • Macior, L.M. 1968. Bombus (Hymenoptera, Apidae) queen foraging in relation to vernal pollination in Wisconsin. Ecology 49:20-25.
    • MacKenzie, K.E. and A. L. Averill. 1995. Bee (Hymenoptera: Apoidea) diversity and abundance on cranberry in southeastern Massachusetts. Annals of the Entomological Society of America 88(3): 334-341.
    • Matteson, K.C. and G.A. Langellotto. 2009. Bumble bee abundance in New York City community gardens: implications for urban agriculture. Cities and the Environment 2(1): article 5. Available online:
    • Plath, O.E. 1934. Bumblebees and their ways. New York, NY: Macmillan Company. 201 p.
    • Ratti, C.M., H.A. Higo, T.L. Griswold, and M.L. Winston. 2008. Bumble bees influence berry size in comercial Vaccinium spp. cultivation in British Columbia. Canadian Entomologist 140(3): 348-363.
    • Stubbs, C.S. and F.A. Drummond. 2001. Bombus impatiens (Hymenoptera: Apidae): an alternative to Apis mellifera (Hymenoptera: Apidae) for lowbush blueberry pollination. Journal of Economic Entomology 94:609-616.
    • Szabo, T.I. and D.H. Pengelly. 1973. The over-wintering and emergence of Bombus (Pyrobombus) impatiens (Cresson)(Hymenoptera: Apidae) in southern Ontario. Insectes Sociaux 20:125-132.
    • Tripoldi, A.D. and A.L. Szalanski. 2015. The bumble bees (Hymenoptera: Apidae: Bombus) of Arkansas, fifty years later. Journal of Melittology 50: doi:
    • Williams, P., R. Thorp, L. Richardson, and S. Colla. 2014. Bumble Bees of North America. Princeton, NJ: Princeton University Press. 208 p.
  • Additional ReferencesLegend:   View Online Publication
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    • Adhikari, S. 2018. Impacts of dryland farming systems on biodiversity, plant-insect interactions, and ecosystem services. Ph.D. Dissertation. Bozeman, MT: Montana State University. 207 p.
    • Adhikari, S., L.A. Burkle, K.M. O'Neill, C.M. Delphia, D.K. Weaver, and F.D. Menalled. 2019. Dryland organic farming partially offsets negative effects of highly simplified agricultural landscapes on forbs, bees, and bee-flower networks. Environmental Entomology 48(4): 826-835.
    • Dolan, A.C. 2016. Insects associated with Montana's huckleberry (Ericaceae: Vaccinium globulare) plants and the bumble bees (Hymenoptera: Apidae) of Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 160 p.
    • Dolan, A.C., C.M. Delphia, K.M. O'Neill, and M.A. Ivie. 2017. Bumble Bees (Hymenoptera: Apidae) of Montana. Annals of the Entomological Society of America. 110(2): 129-144.
    • Doublet, V., Y. Poeschl, A. Gogol-Doring, C. Alaux, D. Annoscia, C. Aurori, S.M. Barribeau, O.C. Bedoya-Reina, M.J.F. Brown, J.C. Bull, M.L. Flenniken, D.A. Galbraith, E. Genersch, S. Gisder, I. Grosse, H.L. Holt, D. Hultmark, H.M. Lattorff, Y. Le Conte, F. Manfredini, D.P. McMahon, R.F.A. Moritz, F. Nazzi, E.L. Nino, K. Nowick, R.P. van Rij, R.J. Paxton, and C.M. Grozinger. 2017. Unity in defence: honeybee workers exhibit conserved molecular responses to diverse pathogens. BMC Genomics 18: 207.
    • Fultz, J.E. 2005. Effects of shelterwood management on flower-visiting insects and their floral resources. M.Sc. Thesis. Bozeman, MT: Montana State University. 163 p.
    • Kearns, C.A. and J.D. Thomson. 2001. The Natural History of Bumble Bees. Boulder, CO. University Press of Colorado.
    • McMenamin, A.J., and M.L. Flenniken. 2018. Recently identified bee viruses and their impact on bee pollinators. Current Opinion in Insect Science 26:120-129.
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Common Eastern Bumble Bee — Bombus impatiens.  Montana Field Guide.  .  Retrieved on , from