Garden bumblebees nest underground in colonies of up to 100 workers, often using old nests of small mammals. They also need moss and dried grass to be present in their habitats in order to successfully build their homes.
A single queen starts a new colony in spring. Queens begin to search for suitable places in which to establish nests. The queens carry out all necessary duties by themselves for over a month until the first batch of workers develops from larvae. In late summer and early fall, new breeding females and males emerge. At the end of the bumblebee season in early October, mated queens search for hibernation sites underground while the rest of the colony dies off