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? I am happy to help but unsure as to what to do.

[Geoff F]

Are you sure that it is Bombus terrestris? They usually prefer to construct underground nests.

Bombus pratorum or Bombus jonellus are quite similar and are known for nesting in a variety of positions.

[RKB]

Might even be the new colonist, Tree Bumblebee (Bombus hypnorum), which likes nestboxes.

Have you seen the Tree Bee?

[woofas]

Do not pretend to be an expert or even an enthusiastic amateur in identifying bumble bees! So please excuse my mis-recognition. As far as I can see the bees entering/leaving the box are all black ie no mid body band, except for the end of the tail which is brown/buff (not white). This does not fit with any of the species shown in the link.
The entrance hole in the tit box is now almost closed - just about a half inch gap at the top. Clearly, I should not "help" them clear the "old" nest material, I suspect that they are bringing it in.
It will be quite interesting to look inside the box when they abandon it.

[woofas]

Following these suggestions, I have done some more research and have identified the bees in my box as Bombus lapidarius (red tailed bumblebee).
Is it unusual for them to use a tit box as a nest site?

[RKB]

No, I've got them in one of mine right now (exactly the same as yours). I also found a nest in an abandoned vole nest.

[woofas]

This photo shows the amount of old nest material the bees have removed from the box so far.

[eucera]

This is B. lapidarius... as suspected!

[woofas]

You may be interested to know that the bees seem to have cleared out most, if not all, of the nesting material. They have now constructed "curtains" from each inside edge of the entrance hole leaving about a half inch gap. With the correct light conditions, I can now see part of the nest but not well enough to distinguish exactly what I am looking at.

Will they have costructed this nest from the base, side or top of the box?