We have had Tree Bumblebees in our garden for several years now - we often see them on the raspberry flowers - see pic.
This year they have nested in our compost heap - the entrance is between two wooden slats at the front of the centre bin. Peter
unsuspectingly heaped a new load of stuff on to the top only to be
confronted with about 6 angry bees whizzing out of the hole and he
actually got stung. When we realised what was going on we also noticed a single bee patrolling up and down outside the nest - we thought it was a "guard" bee but we now know it was a "male on surveillance" because we read an excellent paper on the Bumblebee Conservation Trust website about Tree Bumblebees and their nests. http://bumblebeeconservation.org/images/uploads/Tree_bee_article_2015.pdf
So we know not to create sudden vibrations - Peter has found he can put compost on the adjacent heap very carefully without being attacked! Since we noticed the nest the weather has been awful so I'm not sure how they're getting on.
But you can see how they have spread so successfully - they nest in protected places where badgers can't dig them up and they are quite aggressive.