This richly illustrated field guide examines how galls develop, and their uses, seasonal appearance and growth rate, predators, and defense mechanisms. The “architects” of galls―bacteria, fungi, mites, moths, beetles, flies, midges, and wasps―are explored in depth, and descriptions are paired with illustrations of these gall-inducing organisms and their typical galls. Gall accounts are divided into those that occur on trees, shrubs, and miscellaneous hosts, including native and ornamental plants. The guide contains a useful glossary and a bibliography.