Poison Hemlock Conium maculatum grows vigorously in huge stands on Vancouver Island, and is often a concern for municipal authorities, because of the potential danger of this poisonous plant to children. It is not poisonous to the caterpillars of Agonopterix alstroemeriana, however, and sometimes complete stands of the plants are stripped of all flowers and foliage by enormous numbers of the caterpillars. After it has done its work, the caterpillar pupates, and the moth emerges just a few weeks later. I don’t know how it spends the winter.