On roots, phylloxera overwinter as first instar nymphs. In the spring, as soil temperature rises. nymphs begin feeding on root sap. The spring and summer feeding adults, which are strictly females, reproduce without male fertilization. . New nymphs move to other root areas, begin feeding and cause gall formation. When mature, they will start producing the next generation of eggs. Five to nine overlapping generations can occur during a growing season. In September and October, newly hatched first instar nymphs begin hibernation for the winter.

Return to factsheet Grape Phylloxera - Pest Management Program for Grape Series