If you are writing an ordinance to try to limit killing bees, I would write it carefully. You don't want to make it so draconian that no one can dispose of an aggressive colony that is a problem. You just want to discourage people spraying swarms hanging in trees (there is probably never a reason to kill them) and have them get professional help with bees in a building. Killing bees in a wall usually makes a mess that has to be cleaned up anyway... depending on the wall, of course. But a typical stud wall will be a mess if you kill the bees. But if you make it so they can't get rid of mean bees you will get a backlash and your law will probably get repealed. The people most likely to follow the law are probably the pesticide applicators who don't want to lose their license, but that may result in a lot more calls to beekeepers to rescue the swarm. Home owners probably will pay little attention to it...