Armored Scale Insect Pests of Trees and Shrubs (Hemiptera: Diaspididae)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 U. S. 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