>>often extend vertically 8-12-16 feet or more, depending upon the height of the wall

This building is approx. 24 ft high and at least 2 of the colonies have been there since last year which means the nests could potentially extend the entire height of the wall... 

>>capped the section between the solid poured lines of cement, though 
it certainly makes a person cry to kill stuff that way.

It comes down to practicality, I guess.  I won't take the entire wall apart just to get the queens.

>>bee repellent<< It gets bees flying for sure, but many times the queen is lost and then no one can work around the area for several days after doing this too!

I would vacuum up the bees as they emerge from the entrance hole.  Any airborne bees would try to re-enter just to get sucked into the hose.

Thank you for sharing your experience.

Waldemar 

****************************************************
* General Information About BEE-L is available at: *
* http://www.honeybeeworld.com/bee-l/default.htm   *
****************************************************