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