The bees of the genus Bombus are commonly known as bumblebees, well-known in many parts of Europe and America. There are also quite a number of species in more temperate regions in Asia. Hong Kong has only one species, Bombus eximius, which was strangely only found locally in 1996.
Bumblebees are social bees, but their nests are a lot more simple and less organized than nests of honeybees, their close relatives. The nest site is usually in an existing underground crevice, such as an abandoned rodent burrow. Inside the nest, there are many cells made by the bees, used to store food and also to house the offspring, which are produced solely by the queen. The cells are not hexagonal in shape as in honeybees and social wasps, but are instead round or pot-shaped. Colonies can range in size from a few bees to a couple of hundreds.
Bumblebees are usually quite large compared to honeybees. They range from 11 to 19mm in length; the queens can get larger. They are covered in dense hairs, giving them a furry appearance, and usually show a colour combination of black, orange, yellow, white or tan colours.
Bumblebees are important and beneficial wherever they occur, helping to pollinate many crops in Europe and America. Their long tongue allows them to feed from many flowers ignored by honeybees. They can sting if touched or if the colony is severely disturbed, but most species are not aggressive and a nest in a garden generally poses little threat if people are aware of its existence and avoid disturbing them. The species in Hong Kong is more commonly found out in the New Territories and near forested areas. I have never seen a nest, but it is unlikely that they nest near human dwellings locally.