works on peach and apple trees. WIll also work on rafters that rats use to travel.
Squirrels can "jump" upward and clear a couple feet of covered tree if they are chased, but allowed to go up on their own they will take the path of least resistance. If you ever watch a squirrel climb a tree, they keep their body against the trunk. My best luck with apple trees was pushing the blades in deeply, leaving about 1/4 inch at the bottom and 1/2 inch sticking out at the top. They will see it, but have no way to understand how sharp it is. When they figure it out, its too late, but be warned, it "is" messy. You also dont want kids etc around that might lean up against the tree, there is some liability involved in using this method. Like setting a mouse trap shotgun for other critters. If PEOPLE step into the trap the repercussions can be ugly.