How to Manage Pests

Pests in Gardens and Landscapes

Grape erineum mite—Colomerus vitis

Identification

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.

Life cycle

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.

Damage

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.

Solutions

Control is not necessary. Early leaf distortion can be tolerated with no resulting loss in yield

Grape erineum mites
Grape erineum mites

Erineum mite damage
Erineum mite damage

Upper surface of damaged leaf
Upper surface of damaged leaf

Undersurface of damaged grape leaf
Undersurface of damaged grape leaf


Statewide IPM Program, Agriculture and Natural Resources, University of California
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