What can I do about these kids who want stay off my yard?

We are renting a house in Mississippi and we have some teenage kids down the road that keep riding their dirtbikes and 4wheelers in our yard and we have no trespassing sign and we have asked them to stay away because they are taring the yard up bad and they almost it my three year old daughter and I have called the law,but the law isnt doing anything because they keep coming back so what can I do?