Bumblebees have an annual life cycle. Usually the queen wakes up from hibernation in spring and finds a good nesting location in which to lay eggs. These eggs hatch into sterile female worker bees, which help their mother increase the size of the nest and raise more workers. The colony will expand until the queen decides that it is time to produce new queens and male bees which fly off and mate. The newly mated queens will find somewhere to hibernate through the winter, but the old queen, the males and all the worker bees die and the nest is abandoned. This means bumblebees can be seen throughout spring, summer and into autumn, but they are rarely active in winter.
However over the last 15 years or so, people have started to notice winter activity of a bumblebee commonly found in gardens, the Buff-tailed bumblebee (Bombus terrestris). It appears that rather than hibernating, a small number of newly mated queens are establishing nests in the autumn. This means worker bees can be seen foraging in December and January, with new queens and males emerging in February.
Winter generations have mostly been recorded the southern half of England and the majority of bees are seen in urban gardens, parks and car-parks, where there is access to winter flowering ornamental plants. Mahonia seem most attractive to the bumblebees, along with winter-flowing heathers and honeysuckles.
The Bees, Wasps and Ants Recording Society would like to record data on this new phenomenon and is asking people to send in records to them. So if you see a bumblebee buzzing around your garden, take a closer look to see if it is a worker or male buff-tailed bumblebee. The Bumblebee Conservation Trust’s website can help you with identification.