Grape phylloxera (Daktulosphaira vitifoliae) is a very small, soft-bodied, aphid-like insect. It has a complex life cycle with up to eighteen stages and four distinct forms.
Grape phylloxera is a pest of grapevines around the world. It originated in southeastern United States, where some American grape species developed resistance or tolerance to it. It was introduced into France in 1860 when infected vines were imported for their resistance to powdery mildew. In the next 40 years the pest destroyed nearly two-thirds of wine grape vineyards in Europe.
Grape phylloxera adults are difficult to identify because of their extremely small size. They are usually identified by the galls they produce on the roots and leaves of grape plants. Galls on the tips of rootlets are yellowish-brown, hook-shaped swellings. Galls on larger roots are rounded, wart-like swellings. Galls on the underside of leaves are small, green, rough, and more or less globular.