I have 2 relatively new (planted 1-1/2 years ago) Red Sunset Maple trees. The past 2 springs I have noticed something attacking the leaves on these trees. It it making holes in the leaves and leaving some brown spots on it.

I took a closer look and see that there are very small Caterpillars crawling on it and I think this is what is attacking the trees. Is there anything I can spray on it for this? Preferably something natural based if possible. I am in Northeast PA. Thanks in advance!