Grape phylloxera, Daktulosphaira vitifoliae (Homoptera: Phylloxeridae), is a worldwide pest of grapevines. Its life cycle has sexual and asexual portions with forms that feed from leaf and root galls. Not all forms occur throughout the insect's range. Root forms predominate on Vitis vinifera cultivars; leaf forms predominate on other Vitis species characteristic of the American native range. Other conditions influence expression of the life cycle. Hosts and conditions similarly affect life table performance. Damage to grapevines is by secondary soilborne pathogens attacking the feeding site and by physiological interaction of the insect with the grapevine, though the latter has not been well studied. Resistant rootstocks derived from native American Vitis are the primary control tool. The insect varies genetically and relative to performance on hosts. Use of insecticides is limited in effect, and other control methods are not proven. More research on the biology, ecology, and management of phylloxera is needed.