Tree bumblebee

Elite pollinator of holes in trees

Tree bumblebee. Kuva Mira Lainiola.

Bumblebees (genus Bombus) are stout, usually hairy bees known for pollinating plants. If you are hoping for a good crop of berries or fruit, you must be prepared to welcome bumblebees, the natural pollinators, to your farm in addition to western honey bees. In urban areas, cultivated allotments and allotment gardens are some of bumblebees’ favourite spots.


The pollinating power of bumblebees and other bees is based on their hairy structure developed for the collection of pollen, such as pollen baskets in bumblebees and many species of bees. The basket consists of the tibia of the hind leg and the hairs surrounding it, which catch pollen. Bumblebees collect pollen to feed their larvae and transfer it from flower to flower as they go.


The larvae are taken care of by workers after the first of them have grown up along with all of the tasks important for the survival of the colony.


Unlike western honey bees, overwintering bumblebee queens are the only inhabitants of their nests in the spring. Workers, old queens and males, buzzing around primarily in the late summer, die in the autumn, at the latest, and the queens that were born that summer will remain in the nest to overwinter.


The males do not look after their offspring or the nest, instead, they focus on flying from one flower to the next, i.e. eating and mating. All male bumblebee are, in essence, louts.


Tree bumblebee

Elite pollinator of holes in trees

The tree bumblebee (Bombus hypnorum) is the easiest to identify of all the bumblebee species in Finland. If you want to be able to identify a species of bumblebee, the tree bumblebee is a great candidate. Its body is a reddish brown, its rear is black at the base and middle and white at the tip. This ‘tricolour’ sets it apart from all other bumblebee species in southern Finland.


The name tree bumblebee is quite apt. It nests in a tree, building or bird box, whereas other species will nest on the ground nearly without fail, either sheltered by vegetation or in a hole in the ground.


The tree bumblebee’s behaviour is brazen. The species may be aggressive near the nest, and they have been reported to chase birds away from their boxes when trying to find a place to nest.


Unlike other Finnish bumblebee species, queens try to mate with many males.


The tree bumblebee is a familiar sight in many different cultural environments, even in the centre of Helsinki. In the spring, it visits willow flowers in particular, and in the summer it pollinates raspberries, for example.