Hi out of curiosity are you asked to remove mason bees?
Best to leave masonary bees alone, they will not hurt you, spray treatments to walls nesting sites largley ineffective. Best action would be to re point failing mortar joints after the best have departed. Keep all bees safe where possible
I couldent agree more - I been making mason bee boxs and tubes for last few years and started boxs for others too. You can't beat a beer in front of the boxs and watch them at work!