Bombus auricomus

(Robertson, 1903)

Black-and-gold Bumble Bee, Black and Gold Bumblebee

Bombus auricomus is a large native to eastern North America, ranging from Ontario and Saskatchewan west to the Great Plains. and males measure 1.7–2.0 cm in length, while queens reach up to 2.5 cm. The constructs above-ground nests in open and was historically confused with the Nevada bumble bee (B. nevadensis), but is now recognized as a distinct species. Males exhibit territorial , establishing patrol routes along habitat edges and scent-marking vegetation to attract females.

Bombus auricomus by (c) Navin Sasikumar, some rights reserved (CC BY), uploaded by Navin Sasikumar. Used under a CC-BY license.

Bombus (Bombias) auricomus by the Smithsonian. Used under a CC0 license.

Pronunciation

How to pronounce Bombus auricomus: //ˈbɑm.bəs ɔːˈriː.kə.məs//

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Identification

Distinguished from the Nevada (Bombus nevadensis), with which it was formerly considered , by current taxonomic separation. Specific diagnostic characters for field identification are not provided in available sources. The ' large size and eastern North American distribution may help separate it from western .

Images

Appearance

A fairly large with and males 1.7–2.0 cm long, queens up to 2.5 cm. Coloration features black and gold/yellow patterning typical of the . Specific morphological details distinguishing it from similar are not provided in available sources.

Habitat

Grasslands and other open types. Males establish patrol routes along habitat edges and near visually conspicuous landmarks such as trees.

Distribution

Eastern North America, including Ontario and Saskatchewan in Canada and much of the eastern United States, extending west to the Great Plains.

Diet

Feeds on nectar and pollen from diverse flowering plants including thistles, prairie clovers, delphiniums, teasels, Echinacea, bergamot, penstemons, clovers, and vetches.

Life Cycle

Colonial with queens, , and males. Nests are constructed above ground in open . Specific details of developmental stages and colony are not provided in available sources.

Behavior

Males establish territorial patrol routes along edges and landmarks, returning to favored perches for periods ranging from 2 to 24 days. Males scent-mark vegetation near perches early in the morning, then scan visually for passing females for up to 7–8 hours daily. Non-contact chases between perch owners and intruders occur, with same locations sometimes occupied across multiple years. Male activity begins earlier in the day than in the related Bombus griseicollis.

Ecological Role

of wild flowering plants and likely agricultural crops, though specific crop associations are not documented in available sources. Contributes to pollination of the diverse plant it visits.

Human Relevance

May contribute to pollination of agricultural and horticultural plants. No specific documented economic value or management interactions are provided in available sources.

Similar Taxa

Bombus nevadensisHistorically considered with B. auricomus, now recognized as a separate . The two were previously grouped together under a broader taxonomic concept.
Bombus griseicollisMales of both exhibit territorial patrol route and scent-marking, but differ in timing of daily activity (B. auricomus males patrol earlier) and use of perches (B. auricomus in more open areas vs. B. griseicollis within or shaded by trees).

More Details

Taxonomic History

This was previously treated as with Bombus nevadensis under the name 'Bombus nevadensis auricomus' in older literature. The two are now considered separate species, though some behavioral studies still reference the older .

Male Mating System

The male mating system has been described as resembling a 'pure dominance () mating system' similar to certain vertebrates, involving landmark-based territoriality and scent-marking rather than resource defense.