I planted 2 marsh milweeds this spring. However, over the past week, the number of caterpillars munching on them has grown tremendously (at least 100) and today there are only a couple leaves left for them to eat. They range in size from really large to tiny babies. Will they be able to find another food source, or should I try to relocate them to something they'd like to eat?? I don't want them to die.