I wonder if they just like certain trees? I remember as a kid, my grandpa and the gardner used to take a gasoline torch and burn them out of the trees.
The spraying here for the mosquitoes is about as good as the caterpillars spraying. Zilch in my Area.
My SIL put 4 x 4s along the bottom of the fence where one of the neighbors dog keeps pushing under and between the groundhogs and this dog (who we can not find out who it belongs to,) has our new $$$$$ fence beginning to look years old. Irresponsible pet owners make me sick.
This dog goes under our fence every morning and runs to the next open area. He must weigh 90 lbs he is a big golden retriever.