Bumblebee colonies stay small—sometimes just fifty workers
More than 250 Bombus species make up the only living bumblebee genus in family Apidae. Most are eusocial with one queen, yet nests stay far smaller than honeybee hives—sometimes only about fifty individuals—under fuzzy aposematic pile.
The name joins bumble, an old word imitating a hum, with bee, and the genus name Bombus, coined by Pierre André Latreille in 1802, comes from Latin and Greek words for buzzing. Charles Darwin called them humble-bees in On the Origin of Species in 1859, stressing their role in pollinating clover; bumblebee took over during the 20th century. Not every species plays by colony rules: cuckoo bumblebee queens build no nest of their own but invade another species' colony, kill its queen and leave their eggs to be raised by the resident workers.
Bumblebees belong to the corbiculate bees, named for the pollen baskets on their hind legs, alongside honeybees, orchid bees and stingless bees. Whether advanced social life evolved once or twice in this group has been argued for decades; a 2015 study of gene expression across more than 3,600 genes supported a single origin. The tribe probably arose 25 to 40 million years ago, and about 14 possible fossil species were known by 2019, including one from the Late Eocene Florissant beds of the United States.
They thrive in cold places because they can warm themselves by basking, by shivering their flight muscles and by trapping heat through countercurrent exchange. Species such as Bombus polaris reach Greenland and Ellesmere Island, the northern edge of social insect life. They are native almost everywhere except Australia, where they were introduced to Tasmania, and sub-Saharan Africa.
A long, hairy tongue laps nectar and, at rest, folds under the head; longer tongues reach deeper flowers, and some bees simply bite into a flower's base to steal nectar. Workers and queens secrete flakes of wax from glands on the abdomen to mould honeypots. Their black-and-yellow bands warn of a painful sting, and species in the same region often converge on similar patterns, so predators need only learn one lesson.
Source: Bumblebee
