Bombus

Latreille, 1802

bumble bees, bumblebees

Species Guides

50

Bombus is the sole extant in the tribe Bombini, comprising over 250 of . These bees are distinguished by their ability to forage in cooler temperatures and lower light conditions than many other bees, including honey bees. They perform buzz pollination—vibrating their muscles to dislodge pollen from flowers—a critical for crops such as tomatoes, peppers, and cranberries. Multiple Bombus species significant declines due to loss, exposure, climate change, and transmission from commercial operations. Four California species (B. franklini, B. suckleyi, B. occidentalis, B. crotchii) are under protection consideration, with B. franklini feared extinct since 2006.

Bombus by (c) Leila Dasher, some rights reserved (CC BY), uploaded by Leila Dasher. Used under a CC-BY license.Bombus vandykei by (c) Ken-ichi Ueda, some rights reserved (CC BY), uploaded by Ken-ichi Ueda. Used under a CC-BY license.Bombus vancouverensis by no rights reserved, uploaded by Steve Wells. Used under a CC0 license.

Pronunciation

How to pronounce Bombus: /ˈbɔm.bʊs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from honey bees (Apis mellifera) by larger, hairier, more robust body and rounded . Separated from carpenter bees (Xylocopa) by presence of corbiculae () on hind legs in females. Distinguished from cuckoo (subgenus Psithyrus) by presence of and corbiculate females; cuckoo lack workers and have females without pollen-carrying structures.

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Habitat

Diverse including meadows, grasslands, forests, alpine regions, agricultural areas, and urban gardens. Requires access to flowering plants for foraging and suitable nesting sites, typically underground cavities or dense grass tussocks.

Distribution

Primarily Northern Hemisphere, especially higher altitudes and latitudes. Also present in South America with limited lowland distribution. North America approximately 50 ; California has 25-27 species. Montana records 28 species, the highest state diversity in the United States.

Seasonality

Activity period varies by and latitude. Many temperate species active from spring through fall; some species emerge from hibernation as early as February in mild climates. Colony cycle typically spans one season, with new queens entering in late summer or fall.

Diet

Nectar and pollen from diverse flowering plants. foragers that do not depend on single flower types, though individual show preferences. Buzz pollination allows access to pollen from flowers with poricidal anthers.

Life Cycle

eusocial colony cycle: solitary emerges from , founds nest, lays . First develops into , which then assume foraging and nest maintenance. Colony grows through summer, produces new queens and males in late season. New queens mate and enter diapause; founding queen, workers, and males die. Some tropical may exhibit extended or colony cycles.

Behavior

Buzz pollination: grasps anther with and vibrates wing muscles to release pollen. Capable of foraging at lower temperatures and light levels than honey bees. Foraging rate approximately twice that of honey bees, though higher energy expenditure due to greater body mass. Some are (cuckoo ) that invade nests of other Bombus species.

Ecological Role

Keystone of wild flowering plants and agricultural crops. Provide pollination services estimated at $3 billion annually in the United States. Critical for buzz-pollinated crops including tomatoes, peppers, and cranberries. Facilitate of numerous wild plant ; loss of linked to declines in insect-pollinated plants in Britain and the Netherlands.

Human Relevance

Essential agricultural , particularly for greenhouse tomatoes and field crops requiring buzz pollination. Subject of intensive conservation efforts including the California Bumble Bee Atlas. Four proposed for listing in California due to severe declines. Research focus for understanding pollinator decline causes including neonicotinoid effects, with documented impairment of pollination services at field-realistic exposure levels.

Similar Taxa

  • Apis melliferaHoney bees share general and role, but are slimmer, less hairy, with more elongated and distinct abdominal color banding; lack buzz pollination ability and have lower foraging rates.
  • XylocopaCarpenter bees are similarly robust and hairy, but have shiny, largely hairless and lack corbiculae; females carry pollen on scopal hairs instead.
  • Psithyrus (subgenus)Cuckoo are now often included within Bombus; they lack , have females without corbiculae, and exhibit parasitic .

More Details

Conservation status

Approximately 25% of North American Bombus are at risk. Franklin's (B. franklini), with the smallest known range of any bumble bee, has not been observed since 2006 and is feared extinct. The American bumble bee (B. pensylvanicus) has declined by nearly 90% and is under federal status assessment. declines attributed to synergistic factors: fragmentation, exposure, climate change, overgrazing, competition with managed honey bees, low genetic diversity, and spillover from commercial bumble bee operations.

Foraging energetics

Research demonstrates that and honey bees partition floral resources through differences in foraging energy . Bumble bees' higher mass increases energy costs but their faster visitation rates increase energy gains; outcome depends on flower . On lavender, bumble bees visit flowers at three times the rate of honey bees. This energetic partitioning explains 74% of variation in relative abundance across 22 plant , highlighting importance of plant diversity for coexistence.

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