Tree Bumblebee

Tree Bumblebee (Bombus hypnorum)

As we emptied our moth trap out a couple of weeks ago, we found a cold and dozy bumblebee among the egg cartons piled there. Like the moths she shared the trap with, she'd obviously been drawn in by the light. We boxed her up and carried her out to a stump in the sun, and set her there to warm up, which she quickly did. Soon, she was maneuvering herself to get a better angle towards to the sun (i.e. exposing more of her black self to its rays) and within minutes she zoomed off — circling back a few times to check out the stump as a potential nesting site. Unlike the Buff-tailed Bumblebee that I profiled a few weeks ago, this one has a bright gingery-brown thorax (the part of the bee just behind the head). The female's black abdomen has a white tip. Males would also have some gingery-brown hairs at the ventral end of the abdomen — that is, the end of the abdomen closest to the head. The combination of gingery thorax and white tail tip is unique among British bumblebees.

The Tree Bumblebee is a relatively new arrival to the UK, first recorded in southern England in 2001. It's been rapidly pushing north ever since, arriving in Norfolk in 2008, and now regular well into Scotland. Amazingly, it's now one of the commonest bumblebees in the British Isles. Elsewhere, it's found throughout mainland Europe and Asia, as far north as the Arctic Circle. It's one of the earliest bumblebees to emerge in the spring, flying from March through July. It prefers to feed at pendant-shaped flowers; that said, it's not terribly picky and has been recorded feeding at more than 100 different plant species. As an early-emerging species, it has become particularly important in the pollination of orchards, which have been struggling with the decline of honeybees. Though naturally a woodland edge species, the Tree Bumblebee has quickly adapted to us humans, and will happily use a nest box or the gap under a roof tile as readily as a tree hole for its nest site. Because of their unique nesting spot choices (other bumblebees nest underground), Tree Bumblebees don't appear to be adversely impacting Britain's other bumblebee species. We saw a few checking out our already-occupied nest boxes earlier this year, but fortunately, the Eurasian Blue Tits prevailed.