Different species have different preferences but generally they require dry, concealed cavities, often underground. Bumblebees cannot dig so they use disused burrows made by small rodents, such as mice and voles. It is thought that some bumblebees can faintly smell the rodents that once lived there and follow this scent to the hole.
The queen will use dry grass and moss left by the previous residents of the hole to create a layer of insulation for her own nest. This is a wax cell, in which she lays her first batch of eggs. She then spreads her furry abdomen over the brood and incubates it until the larvae hatch. They must be fed on both pollen for protein and nectar for energy.
Some bumblebees will nest above the ground in piles of dead leaves, dry tussocky long grass, or in abandoned birds’ nests, while other use banks of soil that catch the sun.