I went on a 2 week vacation in early July. A friend took care of watering my gardens during that time. When I returned, I found approx. 20 of these huge green caterpillars with red horns and yellow eyes (the size of my index finger) devouring my tomato plants. They were even able to destroy the fruit by biting into it. What could I have done proactively, to have avoided this situation please?