White-shouldered Bumble Bee - Bombus appositus
Mountain Bumble Bee,
For definitions and diagrams of bumble bee morphology please see the Montana State Entomology Collection's Bumble Bee Morphology page
. A long-tongued, large-sized bumble bee: queens 20-24 mm in length, workers 11-18 mm. Head long, cheek distinctly longer than wide; mid leg basitarsus with far back corner narrowly extended in a spine, outer surface of hind leg tibia flat and lacking hair (except fringe) forming pollen basket; hair of face pale whitish and lighter than hair on T1; sides of thorax predominantly black, upper surface pale at least anterior to wings and bordering a black band between wings; T1-5 straw yellow or brownish orange. Males 10-16 mm in length; eyes similar in size and shape to eyes of any female bumble bee; hair color pattern similar to queens and workers, but sides of thorax with only a few black hairs intermixed toward back; T6 pale at sides (Koch et al. 2012, Williams et al. 2014).
Across range, queens reported April to October, workers May to September, males May to October (Williams et al. 2014). In Utah, queens reported May to August, workers May to September, males June to September (Koch et al. 2012); in California, queens early May to early September, workers late May to late August, males late June to early September (Thorp et al. 1983).
Please see the Montana State Entomology Collection's Key to Female Bumble Bees in Montana
. Females told from other Montans Bombus
by a combination of outer surface of hind leg tibia concave and hairless (except fringe) forming pollen basket; cheek longer than wide; yellow or pale white hairs on face, sometimes with black giving a cloudy appearance; T1-5 straw-yellow or orange-brown.
Resident Year Round
Recorded Montana Distribution
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Throughout the mountain west, from southern British Columbia and southwestern Alberta south in the Cascades and Sierra Nevada to central California, and west of the Great Plains in the Rocky Mountains to southern New Mexico; also in the Black Hills of South Dakota (Koch et al. 2012, Williams et al. 2014). In Colorado, found at 1600-4000 m elevation, but most common below 2900 m (Macior 1974). In California, to at least 2740 m elevation (Thorp et al. 1883); in Montana, to at least 3050 m in the Beartooth Mountains (Bauer 1983). Common over much of range (Koch et al. 2012).
Grassland, fields, sagebrush steppe, aspen parkland, riparian woodland, montane meadows, granitic soil types, above treeline in alpine tundra (Hobbs 1966b, Macior 1974, Richards 1978, Bauer 1983, Wilson et al. 2010, Cook et al. 2011, Miller-Struttmann and Galen 2014, Williams et al. 2014). Also infrequently in commercial Vaccinium croplands (Ratti et al. 2008).
Feeds on a variety of flowers, including Aconitum, Agastache, Astragalus, Balsamorhiza, Brodiaea, Castilleja, Cirsium, Delphinium, Dipsacus, Erysimum, Frasera, Gentiana, Helianthus, Iris, Lineria, Lonicera, Melilotus, Mentha, Monarda, Myosotis, Orthocarpus, Oxytropis, Pedicularis, Penstemon, Phacelia, Rhus, Rudbeckia, Solidago, Thermopsis, Trifolium, and Vicea (Macior 1974, Bauer 1983, Thorp et al. 1983, Mayer et al. 2000, Wilson et al. 2010, Koch et al. 2012, Miller-Struttmann and Galen 2014, Williams et al. 2014). An infrequent visitor to commercial Vaccinium (highbush blueberry) crops in southern British Columbia (Ratti et al. 2008).
Nests built underground, on ground surface, or above ground. In aspen parkland of southern Alberta, 29.3% of 99 nests built underground, 39.4% on the ground surface, and 31.3% above ground (Richards 1978). In wooded foothills of the Alberta Rocky Mountains, Hobbs (1966b) reported this species in 29 underground and 74 surface hives, and later in 30 underground and 37 surface hives when given a choice at each hive location. Queens sometimes invade nests of conspecifics and attempt to usurp them. Nests are established in southern Alberta from late May to mid July (Hobbs 1966b, Richards 1978); a minority of nest entrances are camouflaged. This bumble bee species does not produce large colonies. First broods average 13 pupae, which require an average of 23-26 days for rearing the first workers. In second and third broods, an average of 3.6 eggs are laid per cell, later broods may contain up to 8 eggs per cell. Typically, only two broods of workers are produced; average number of pupae (cocoons) per colony per year ranged from 68 to 168. Males hover and perch outside nest entrances and wait to mate with emerging queens, possibly mating within nests (Hobbs 1966b). Parasitized by the cuckoo bumble bees Bombus insularis, B. suckleyi, and B. fernaldae, which sometimes succeed in having the host workers raise their young (Hobbs 1966b, Williams et al. 2014).
- Literature Cited AboveLegend: View Online Publication
- Bauer, P.J. 1983. Bumblebee pollination relationships on the Beartooth Plateau tundra of Southern Montana. American Journal of Botany. 70(1): 134-144.
- Cook, S.P., S.A. Birch, F.W. Merickel, C.C. Lowe, and D. Page-Dumroese. 2011. Bumble bee (Hymenoptera: Apidae) community structure on two sagebrush steppe sites in southern Idaho. Pan-Pacific Entomologist 87(3): 161-171.
- Hobbs, G.A. 1966b. Ecology of species of Bombus Latr. (Hymenoptera: Apidae) in southern Alberta. V. Subgenus Subterraneobombus Vogt. Canadian Entomologist 98: 288-294.
- Koch, J., J. Strange, and P. Williams. 2012. Bumble bees of the western United States. Washington, DC: USDA Forest Service, Pollinator Partnership. 143 p.
- Macior, L.M. 1974. Pollination ecology of the Front Range of the Colorado Rocky Mountains. Melanderia 15: 1-59.
- Mayer, D.F., E.R. Miliczky, B.F. Finnigan, and C.A. Johnson. 2000. The bee fauna (Hymenoptera: Apoidea) of southeastern Washington. Journal of the Entomological Society of British Columbia 97: 25-31.
- Miller-Struttmann, N.E. and C. Galen. 2014. High-altitude multi-taskers: bumble bee food plant use broadens along an altitudinal productivity gradient. Oecologia 176:1033-1045.
- 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.
- Richards, K.W. 1978. Nest site selection by bumble bees (Hymenoptera: Apidae) in southern Alberta. Canadian Entomologist 110(3): 301-318.
- Thorp, R.W., D.S. Horning, and L.L. Dunning. 1983. Bumble bees and cuckoo bumble bees of California (Hymenoptera: Apidae). Bulletin of the California Insect Survey 23:1-79.
- Williams, P., R. Thorp, L. Richardson, and S. Colla. 2014. Bumble Bees of North America. Princeton, NJ. Princeton University Press.
- Wilson, J.S., L.E. Wilson, L.D. Loftis, and T. Griswold. 2010. The montane bee fauna of north central Washington, USA, with floral associations. Western North American Naturalist 70(2): 198-207.
- Additional ReferencesLegend: View Online Publication
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- Kearns, C.A. and J.D. Thomson. 2001. The Natural History of Bumble Bees. Boulder, CO. University Press of Colorado.
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