Genus: Bombus Latreille, 1802
Common names: bumble bees or bumblebees
Bumble bees are well known due to their bright colors, large body size, flower-visiting activity during daylight hours, and overall abundance. They are important pollinators of both crops and wildflowers. Bumble bee species are declining in Europe, North America, and Asia due to several factors, including loss of food plants and nesting sites, pesticide exposure, and pathogens.
Bumble bees are typically found in temperate climates. They are most abundant and diverse in humid, cool sites rich in flowers, such as mountain meadows.
Bombus is found throughout North America where there are 43 species in the west, 24 species in the east, and 18 in the south (Thorp et al. 1983). A total of 260 species in 15 subgenera are found worldwide, including the Arctic (Williams 2021). Bombus species are only present in northern Africa and are not native to Australia, though they were introduced to Tasmania (Asher and Pickering 2017).
Distribution of Bombus by GBIF: https://www.gbif.org/species/1340278
Worldwide there are about 260 species in 15 subgenera.
Most bumble bees build nests with a queen and workers. However, bumble bees in the subgenus Psithyrus, also known as cuckoo bumble bees, are brood parasites. Psithyrus females do not collect pollen themselves, but will enter a bumble bee colony and kill or subdue the queen. An invading female uses pheromones and physical attacks to force the workers of the colony she's entered to feed her and her young.
Mated, overwintered queens emerge from their hibernacula in very early to late spring, depending on the species. They then begin building nests and provisioning the cells with balls of pollen and nectar. Workers emerge in late spring to early summer after which they build in numbers and persist until late summer to late fall depending on the species. Most colonies have between 50 and 400 individuals. Many species nest underground, using old rodent burrows or similarly sheltered places; they actively avoid places that receive direct sunlight to avoid overheating. Other species make nests above ground in thick grass or tree holes. Virgin queens and males appear in summer to fall, depending on the species, and visit flowers at that time along with foraging workers. At the end of the season workers and males die and newly mated queens enter their hibernacula where they remain dormant until spring. In warm areas such as southern California and South Florida, bumble bees can be found flying even in mid-winter.
Four European species of Bombus have been introduced to Tasmania and New Zealand (Asher and Pickering 2017). The European species, Bombus impatiens, has been introduced into parts of the United States for blueberry pollination.