Friend or Foe?

I've discovered what looks like some kind web/cocoon in a crack in my Victoria Plum.

It wasn't there when I winter washed the trees a couple of weeks ago. My first instinct is to blast it out with the hose but I thought I'd best check first in case it was something beneficial.
Any ideas what it is?

It wasn't there when I winter washed the trees a couple of weeks ago. My first instinct is to blast it out with the hose but I thought I'd best check first in case it was something beneficial.
Any ideas what it is?
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I think the round hole has been made by a hibernating carpenter bee and the silk web is maybe hiding a spider.
@BenCotto Dusting in the garden? That's never gonna happen 😂 I barely have time to dust at work and I'm a cleaner! A spider is my hope as I don't have to worry about that doing any damage to my Victoria plum. I'm more than happy to let anything stay that doesn't leave a path of destruction in its wake!
I certainly wouldn't worry about the spider, or the bee, if @pansyface's correct. They wouldn't cause any problems to the tree
Damage to the cambium or the phloem and xylem layers either side can cause problems, hence @Fairygirl's comment.