These little green caterpillar are attacking the columbine in my garden. They are hungry little buggers and can decimate a plant in short order. But I have been moving away from the use of pesticides and trying less harmful, less lethal approaches like spraying affected plants with a strong stream of water from the garden hose to discourage them from sticking around. So, for now this more harmonious approach seems to be the way to go. But if those damn little green vermin begin to attack my Japanese Maples....it might get ugly.