European Tree Bees

It would be today of all days!  I have noticed that a number of bees have been going in and out of a hole in the cavity wall of our home.  Whilst I appreciate bees and all they do for us, I don't want them setting up a colony by the back door.  I contacted the local bee-keeper and he has advised me that they are European Tree Bees and as long as we leave them alone, they will leave us alone.  He suggests that I leave them be until October when they will fly off and I can seal up the hole.  They will not be producing any honey.