How to Manage Pests

Seasonal development and life cycle—Erineum mites

Erineum mites overwinter under outer bud scales and move to unfolding leaves in spring. They associate in small groups to feed on lower leaf surfaces; the result is production of masses of enlarged leaf hairs inside a blisterlike area on the leaf (the erineum). On the undersides of the leaves, beneath the swellings, are concave, densely lined, felty masses of oversized leaf hairs in which the mite populations develop. As the population increases, some move to new areas or to other leaves and form new erinea. From mid-August to leaf drop, there is a movement from the erinea back to the overwintering site underneath the bud scales.

Upper surface of leaf

Undersurface of grape leaf