Bees in Tit box

[woofas]

It appears that a colony of Buff Tailed Bumble bees have taken over a tit box in our garden. I notice that the entrance now has plant detritus partially blocking the hole.
Are the bees clearing out the remains of the tits' old nest or are they carrying in new nesting material? I am happy to help if they are trying to clear away the rubbish but am unsure as to what to do.
I have noticed a couple of bees at the hole with their wings flapping - are they trying to cool down the colony?

[wildwood]

Lucky you. It is hard to say at what stage the colony is but I wouldn't interfere with the nest, leave them to it.

Here's a bit of info on your lodgers http://www.dgsgardeni...rnet.co.uk/bumble.htm