Hello, I have a small fruit tree orchard near my home. Over the past several years some kind of borer insect has been destroying our older trees, but recently they have almost completely killed a younger cherry tree. On the cherry trees, they make large piles of sap crystallize where they go into it. I chipped away a pile of sap today and cut into tree near a small hole. The hole goes in a little ways and when it hits the harder, center wood, it goes down parallel, but it seems to not be able to cut the hard wood. The tunnel is only a couple of millimeters wide. I have never actually seen the creatures. The tunnels are empty now. On the apple trees, they make the branch die, and the bark peels away from the branch like a scroll. Most of the old apple trees have died. One old cherry tree that was very large completely died. They are also attacking the one plum tree we have. They are killing an old dwarven peach tree. Our young peach dwarfs are healthy. Most of our young apples are healthy. I want to stop this very badly, my favorite summer apple trees are starting to go down. I'm going to start grafting twigs from my favorite attacked trees onto the younger trees, so I don't loose them. I'm still not positive what insect is doing this, but right now I have a large supply of permethrin. If I spray in the summer often, will this kill them? I really want to know how to keep my orchard alive. My dad doesn't even want to get new trees until the bores are gone.