Turn the water sprinkler on the moth balls so it dissolves them, if let in a dry area mothballs can last up to a year. WHy your at it flood there yard out.
Why I mentioned long ago about the cease and disist letter thats been wrote by a lawyer and has been handed to them like a summons and signed to know they got the letter that can be added to the documents that you had this said letter drawn up and they read the letter. Even get a copies of...
What about putting a electric fence on yours so if he tries to cross over pop, nothing too harsh just a good reminder he is tresspassing, but might make matters worse. Its best to let the law take place, if you have everything in order according to the plans let the judge see it and laugh them...