Bombus griseocollis

(De Geer, 1773)

brown-belted bumblebee, brown-belted bumble bee

Bombus griseocollis is a widespread North American bumblebee commonly known as the brown-belted bumblebee. It is notable for its flexible use, occurring in both natural and heavily urbanized environments including densely populated cities. The species maintains stable across much of its range, in contrast to many declining North American bumblebees. It exhibits primitively eusocial colony organization with temporal division of labor among .

Bombus griseocollis by no rights reserved, uploaded by USGS Bee Inventory and Monitoring Lab. Used under a CC0 license.Bombus (Separatobombus) griseocollis by the Smithsonian. Used under a CC0 license.Bombus (Separatobombus) griseocollis by the Smithsonian. Used under a CC0 license.

Pronunciation

How to pronounce Bombus griseocollis: /ˈbɒmbəs ˌɡrɪziˈoʊkəlɪs/

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Identification

The brown-yellow abdominal band on (variable and not always present) distinguishes this from some similar bumblebees. Males are identifiable by their exceptionally large relative to width. The species lacks the extensive black coloration on the seen in some other Bombus species. Queens show the distinctive black with yellow-banded segments.

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Appearance

Queens measure 2.1–2.3 cm long and approximately 1 cm wide at the . The and are black with scattered yellow hairs. The is covered in yellow hairs. The abdomen displays yellow bands with black, with a black and black surface. Legs are black. are smaller than queens, sometimes less than 1 cm long, with similar coloration but may show a brown-yellow band around the abdomen. Males measure 1.5–1.9 cm long and approximately 0.7 cm wide at the abdomen, with very large spanning about two-thirds the width of the head. The face and thorax have yellow hairs, and the abdomen is banded with yellow, yellow-brown, and black. are white, robust, and slightly curved, averaging 2.91 mm in length (range 2.8–3.1 mm) with diameter range of 0.8–1.00 mm.

Habitat

Occupies diverse types including meadows, wetlands, agricultural fields, and urban areas. Has been documented in densely populated cities including gardens in New York City and at extreme elevations (observed near the top of the Empire State Building over 100 stories above ground level). Nests are constructed underground or on the surface.

Distribution

Native to much of the United States except the Southwest, and to the southernmost regions of several Canadian provinces (excluding the Maritimes). Present in the southern parts of most Canadian provinces.

Diet

Feeds at many plant including milkweeds (Asclepias), prairie clovers (Dalea), echinaceas (Echinacea), loosestrife (Lythrum), bergamot (Monarda), pickerel weeds (Pontederia), rudbeckias (Rudbeckia), goldenrods (Solidago), clovers (Trifolium), and vetches (Vicia). Queens particularly favor legumes (Fabaceae).

Life Cycle

Colonies are generally small, with fewer than 50 . Nests are established underground or on the surface. The is eusocial with reproductive and non-reproductive . are white, robust, and slightly curved, measuring approximately 2.91 mm in length.

Behavior

Exhibits primitively eusocial organization with temporal division of labor based on shifting patterns of principal tasks rather than discrete age . of all ages perform all daily tasks, with task ensembles changing quantitatively as workers age. Young workers tend to perform in-nest tasks while older workers transition to foraging; in the absence of foraging mortality, foragers may shift back to nursing tasks and be replaced by younger bees. Colony ontogeny influences worker behavioral ontogeny, with significant differences in task performance among workers born in different phases of colony development. Workers perform diverse tasks including wax secretion for nest construction, nest insulation using harvested materials, pupal incubation by wrapping bodies around cocoons, larval feeding via food regurgitation, wax recycling from discarded pupal cases for construction, alarm buzzing, nest inspection and patrol, and foraging. Males exhibit perching , waiting in areas where young queens might pass for mating opportunities. Males scent-mark perches using labial gland secretions containing tetradecyl acetate and butyric acid, likely as signals to other males rather than females. Unusually among bees, males participate in pupal incubation by wrapping around cocoons and pumping the , though they cannot raise temperatures as high as queens. Multiple individuals of either sex may simultaneously incubate a single pupa. Colonies aggressively defend their nests. Shows unusual resistance to conopid mind control, with only 18% of infected individuals succumbing (approximately one-quarter the rate of other bumblebee ).

Ecological Role

Important of diverse wild flowering plants and agricultural crops. Performs buzz pollination on suitable flowers. Serves as to including conopid flies (Thick-headed flies), though with lower susceptibility than other bumblebee .

Human Relevance

Common in urban gardens and agricultural settings. Stable make it a reliable pollination service provider in anthropogenic landscapes. Not considered threatened.

Similar Taxa

  • Bombus vosnesenskiiBoth are common, widespread North American bumblebees with yellow thoracic coloration, but B. vosnesenskii has a black and lacks the brown belt variable on B. griseocollis ; B. vosnesenskii is primarily western while B. griseocollis is more eastern and central in distribution.
  • Bombus impatiensSimilar size and general color pattern with yellow-banded , but B. impatiens has a more uniform yellow without the scattered black hairs, and lacks the brown abdominal band; B. impatiens is also more eastern in distribution with less overlap in the western parts of B. griseocollis range.

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