My question involves personal property located in the State of: Oregon
My family just recently moved into a former rental property owned by us in June. The house had been relatively abandoned for several months while we were trying to rent it. During this time of unoccupation, the neighborhood kids varying in age from toddler to teen (approximately 10 children in all), decided that our yard was perfect for playing in and using as a cut-through to get to our rear neighbor's yard.
I have repeatedly told as many of the children that I can find how the house is no longer available to play around. I've spoken to them on several occasions with escalating seriousness. I don't want to be mean and I certainly don't want to create a bad neighbor environment, but these children have absolutely no respect for personal property. These children repeatedly play on/near my two cars and have scratched the bodywork of both vehicles, they have played near our side yard where we have several pieces of lumber that can be dangerous to play around. They also tamper with a small garden fence we have as well as two reflectors and their latest escapade involves tampering with several motion detector alarms that I had installed while I was going to be away from the house. The previous incidents (other than the car damage) I could almost excuse, but the motion detectors were mounted on the sides of the house, which would be CLEAR trespassing. What can I do as a homeowner without a fence?
I have threatened the children with telling their parents and calling the police, but we live in such a small town that the police department is a county sheriff, not city police. Does that change whether or not a trespassing law would be a higher crime? I don't really want these kids arrested, just scared enough to get it through their thick skulls. I have told them the same thing no less than 7 times, with absolutely no effect! I'm getting at my wits end with these kids and some of their parents work in a mill where they're gone at odd hours and we don't have a regular mail box where I can just drop a note to several parents at once. I'm just not sure what to do to address this issue.
I appreciate any help or guidance about what scale of a crime this would be in the state of Oregon. Thanks!

