A few days ago I was asked to remove bees from a tree in someone's yard.  When I got there, I found a large, mature live oak with a lot of bees on it...thousands... but no cavity anywhere.  Hence, no colony to collect.  I'd not seen bees on oak trees like that before, but now that I look around I find them on all the live oaks around here.  They seem to be foraging on those little brown balls tha…