How to Manage Pests
Pests in Gardens and Landscapes
Grape erineum mite—Colomerus
Adult mites are wormlike, light yellowish white, 0.2 mm long and one-fourth as wide. They have two pairs of legs and are much smaller than spider 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.
Young leaves show bright pinkish or reddish swellings on upper surfaces. Corresponding areas on lower surfaces are concave and densely lined with a felty mass of plant hairs.
Control is not necessary. Early leaf distortion can be tolerated with no resulting loss in yield
Grape erineum mites
Erineum mite damage
Upper surface of damaged leaf
Undersurface of damaged grape leaf