The past two weeks have been pretty rough for my young oaks and apples with these tent caterpillars. I've sprayed with neem oil a couple of times and manually removed them, but I still get a couple off each day. They're frustrating. They partially defoliated a couple of my SWO seedlings in tubes and hit a burenglish pretty good. I'm waiting for the impending arrival of the Japanese beetles on my chestnut trees.
The one that really did some damage I had to look up, I believe it was a cabbage worm. It cut all the leaves off one of my grafted trees at the stem, it is coming back now but I was afraid it was going to die!