I have a fire department regulation size extinguisher filled with water that has a range of about 50 feet. I sneak up and give them a shot. It stings good but does not cause any lasting harm, since they are someones pet and I could not bring myself to hurt one. The best part? They all seem to remember the nasty woman in the green house with the water!! They tend to go away for a long time. It is humane and they get the point.