Spruce spider mite

Oligonychus ununguis

spruce spidermite damage

This mite overwinters in the egg stage on buds and needles. It is active during cooler weather in spring and fall. Nymphs are present in spring as saucer magnolia or Norway maple begins to bloom. Look for active spruce mite infestations in the fall as goldenrod is blooming. Hosts for spruce spider mite include fir, pine, yew, arborvitae, juniper and Douglas-fir. The size of the mites is less than 0.5 mm.

Damage

Look for stippled needles, especially on older growth. Mites will be visible with a 10x hand lens. Old eggshells will be clear; viable eggs are red. Young nymphs are red, turning dark green as they mature. Webbing may be present.

spider mite crop

Management

Sampling mite populations by shaking an infested branch over white paper will help to estimate populations. Low numbers may be controlled by predatory mites if they are present. If miticides are needed, select specific miticides that spare predators.

spruce spider mite

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The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the AgBioResearch, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.