Cuckoo bumblebees
In addition to social bumblebees, we also have nine parasitic species of cuckoo bumblebees that do not build their own nests or establish their own colonies. Instead, they invade existing nests of social species and drive out or kill the queen. Cuckoo bumblebees do not produce workers, only queens and drones. They are cared for by the workers of the displaced queen and raise their own offspring off them.
To determine whether a bumblebee is a social bumblebee or a cuckoo bumblebee, it's worth looking at the hind legs of the female. If you see pollen there, it's a social bumblebee. If there's no pollen, you need to look at the "thigh" of the hind leg to see if it's hairy or bare and shiny. If the leg is completely hairy, it's a cuckoo bumblebee.
Particularly striking is the large red-black cuckoo bumblebee (Bombus rupestris), which stands out due to its dark-colored wings. It therefore resembles carpenter bees, only with a red "bottom."
Natural nesting sites
Social bumblebees usually nest in existing cavities in the ground, for example, in abandoned nests of mice and other rodents. Some also nest above ground in patches of grass and moss. Garden bumblebees or stone bumblebees can sometimes be found in barns or attics. Tree bumblebees build their nests in tree hollows or sometimes in bird nesting boxes.
Bumblebee boxes
You can provide the bumblebees with an artificial bumblebee hive. However, you should be aware that there's no guarantee that a queen bumblebee will move in. If the hive becomes colonized, it must be thoroughly cleaned every year. You should also watch for wax moth infestation.
In addition to commercially available wood-concrete bumblebee boxes, you can also build your own from cardboard or wood. Those who feel confident about keeping bumblebees can find instructions in the recommended books in the information section.
Food plants
Bumblebees are mostly polylectic wild bees, meaning they can use nectar and pollen from many plants. They therefore benefit from a flower-rich garden. One exception is the Alpine Monkshood Bumblebee (Bombus gerstaeckeri). With its very long proboscis, it is perfectly adapted to the poisonous monkshood as its food plant.
Bumblebees help with pollination
Bumblebees are valuable pollinators. They are well adapted to colder conditions because they can actively heat up their flight muscles and are densely hairy. This is why bumblebees pollinate our fruit trees, even in colder weather. They are also important for pollinating tomato plants; they are used commercially for this purpose in greenhouses. As a result, bred bumblebee colonies—along with their pathogens—are sent all over the world. Unfortunately, some of them escape into the wild and compete with native wild bees. Therefore, the trade in bumblebee colonies should not be supported under any circumstances.
