University of Maryland Extension

Eriophyid Mites

eriophyid mites
Closeup of eriophyid mites

Adult eriophyid mites are very small (<1mm). They are spindle-shaped, with four legs and may be white, yellow or orange. You will need a hand lens to see them. There are several generations a year and overwinter in bark crevices and under bud scales. Some species feed on the leaf surfaces of both deciduous and needled evergreen trees causing the foliage to turn olive-tan. Others cause leaf galls (some appear fuzzy) on beech, leaf blisters on pear or damage buds of yew and flowers of ash. Eriophyid mites may cause witches’-broom galls in hackberry, Scotch pine, and poplar.
 

Management

To check for eriophyid mites, look for off-color foliage, leaf or bud abnormalities. Use a 10X or 20X hand lens. Large mite populations often produce many elongate, white shed skins. Plants with a history of eriophyid mite damage should receive a dormant oil spray to kill overwintering stages. To prevent heavy gall infestations, spray with horticultural oil at bud break (summer rate). Leaf feeding mites can be controlled with a spray of horticultural oil (summer rate) whenever they reach damaging levels. Check horticultural labels carefully for instructions and safety precautions.

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