Here's the story. This place that we go to upstate new york was literally infested with caterpillars. They were everywhere and killed all the leaves on the trees. Now, while i was mowing the lawn at out house in Pennsylvania i noticed them there too. There werent that many, but enough to do some damage. Is there some type of chemical that can be used to kill them, but not harm the apple trees that we have? I was thinking of buying the chemical and hooking it up to my power wash and just spraying all the trees. Any ideas on how to get rid of them?