Armored scale insects are among the most damaging and least understood of the pests that prey on forest trees, fruit and nut crops, landscape ornamentals, and greenhouse plants. The passage of United States plant quarantine laws was prompted by devastation caused by an armored scale in the nineteenth century, and the appearance of new invasive species remains a vital concern at ports of entry and for arborists, farmers, nursery workers, foresters, and gardeners everywhere. This book provides the most comprehensive available information on the identification, field appearance, life history, and economic importance of the 110 species of armored scale insects that are found in the United States. The authors have devised the first field key to economic armored scales, which will be invaluable to those trying to identify the pests and prevent the introduction of new exotics. (Most of the species covered are not native to the U.S. but broadly distributed across the globe.) The extensive color plates and highly detailed line drawings surpass anything available in other volumes on armored scale insects, and have not previously been published. Especially noteworthy are the data on distribution, host plants, and the kinds of damage caused by armored scales. The species descriptions include scientific names, synonyms, common names, field characteristics, microscopic characters, affinities, host plants, distribution by state, life history, economic damage, and selected references.