The red-tailed bumblebee is now common throughout the British Isles. A few decades ago none were to be seen in the north but now they are one of the commonest bumblebees to be found in Scotland.
Queens will emerge from diapause (insect hibernation) from March onwards and are up to 22mm long. Their bodies are big, black and hairy with an orange-red tail. They will then seek a suitable nesting site to start a new colony preferring the base of dry stone walls and holes in the ground. They will frequently occupy holes vacated by mice. At the peak of the season the colony can number between 100 to 200 bees. Nearly all of these will be workers which will be much smaller replicas of the queen.
They prefer to extract nectar from such flowers as daisies, dandelions and thistles. These flower heads consist of many small florets which only contain a minimum amount of nectar. However the bees’ strategy is to obtain maximum yield for a minimum effort and time spent foraging as they will walk over the flower head probing each floret in turn.
The male red-tailed bumblebee is the only member of this family to have yellow hair on his head and thorax. They do not collect pollen as they have no pollen sacks. Each male will patrol a mating circuit laying down pheromones to attract potential new queens. At the end of the season the colony dies out and only the newly mated queens will survive the winter. To do so they will seek out a sheltered, dry, dark place to hibernate.