Tree Bumblebees in Nestbox

While checking the bird nest-boxes in his garden recently, Andy M noticed that one nest-box seemed to have been filled with moss, so much so that the moss was visible through the entrance hole.  On watching for a few minutes, a number of bumblebees were seen coming and going from the nest-box.  According to 'Bumblebee Conservation', the Tree Bumblebee (Bombus hypnorum) was first seen in UK relatively recently (2001), presumably arriving from mainland Europe, and has since spread throughout Britain. Seen mostly in late spring and early summer, it can be distinguished from other bumblebee species by its characteristic ginger-coloured thorax, black abdomen and white tail - and from its habit of setting up home in nest-boxes!