Very sad, there is a Red Tail Bumble Bee nest under the hedge outside our office too and that seems to have gone now.
Many a lunch hour spent watching the industrious little insects come and go.
I have noticed recently that Bumble Bees are dying at an alarming rate, outside my office there are at least 10 dead Bees in the small smoking area/patio.
Is this normal for this time of year or is there something more sinister at work.