magooch, I have some paper shell pecan trees that are big producers, so I am continually fighting the little cusses. They are a native species here, and the neighborhood is covered with them. They have chewed the phone lines on the poles to my house in two TWICE, even getting past the squirrel wire the phone company puts around the terminals. They got into my parents attic several years ago, and when I was squirrel proofing it, I found they had been there for years. There was an accumulated nest about 3 feet high, and 4 feet across. It's a wonder the sheet rock in the garage had held it up.
The three methods that work are: CB caps and a 22 rifle, live traps with peanut butter, and if your handy, you can silver solder a sharp nail on the bail of a rat trap, and screw the trap into a tree or board, and then bait it with peanut butter. It is most times deadly.
I also have a Jack Russel Terrier in the yard, but sometimes they make it to the trees, and I have to take care of it then, because they can't get down, and he won't give up for days.