New bees in the garden

My house in Swaffham has cavity walls, and when I had a new bathroon suite installed a couple of years ago an overflow pipe was removed, leaving a small hole allowing access to the cavity.  Last year it was used as a nesting site by a pair of blue tits, but this year it has been taken over by the hole nesting Tree Bumblebee, Bombus hypnorum.  These bees have been very active, collecting pollen in the garden and taking it back to the nest.  On warm days one or two bees station themselves at the entrance to the hole fanning their wings to increase ventilation.

Bombus hypnorum

B hypnorum was first reported in the UK in 2001, and has now established itself over most of the country.  They are distinctive little bees, with white tails and a rusty brown thorax.  They regularly form colonies above the ground, using various holes in trees, buildings, and often use bird nest boxes.  An useful information sheet can be found here: http://hymettus.org.uk/downloads/Info_sheets_2010/Bombus_hypnorum_infosheet.pdf

It is the first time I have seen these bees in Swaffham, but have since also identified them down in Suffolk.