What would you do if a neighborhood kid lobbed a rock at your home with a sling-shot?

I've told this kid numerous times to stay away from my home and property and stop harassing the boy I'm raising. He lobbed a rock at my house on Sunday and hit it. Yesterday he had a long stick and was after something in the tree in my house. Had gotten fed up and went out and told him to leave and never come back to my yard. His excuse was that the boy was staring out at him through his bedroom window (our home, our window, he has a right to watch out the window). Told him next time I'd call the police and let them talk to his mother.