I had loads of them on pecan tree. I saw a few on crepe mytles too.
When I asked about them they just shrud their shoulders and said not to worry over them.
One year when I saw them bad I took a bamboo stick and pulled off tree. I think I did manage to spray something on it.
Last year I didn't see any.
This year I have not seen any yet.
I asked the tree guy where caterpillars come from..he said
they are carried by the wind.