Spruce needles turning brown with fine webbing

What it is

Spruce spider mites are tiny relatives of spiders that feed on the contents of needle cells. Their feeding creates pale speckles that can merge into bronzed or brown areas, and they spin fine silk around needles. ([extension.colostate.edu](https://extension.colostate.edu/resource/spider-mites/))

Also called: Oligonychus ununguis

Plants affected: Spruces, especially dwarf Alberta spruce; also arborvitae, juniper, hemlock, Douglas-fir and some pines. ([extension.psu.edu](https://extension.psu.edu/spruce-spider-mite?utm_source=openai))

Symptoms

• Tiny yellowish speckles on needles, progressing to rusty brown discoloration. ([extension.psu.edu](https://extension.psu.edu/spruce-spider-mite?utm_source=openai))
• Fine silk between needles, especially around their bases. ([ipm.ucanr.edu](https://ipm.ucanr.edu/home-and-landscape/pine-and-spruce-spider-mites/))
• Damage often starts on older needles in the lower, inner branches; heavily affected needles may drop early. ([extension.psu.edu](https://extension.psu.edu/spruce-spider-mite?utm_source=openai))

Causes

• Feeding by spruce spider mites, which are usually most active during spring and fall rather than midsummer heat. ([ipm.ucanr.edu](https://ipm.ucanr.edu/home-and-landscape/pine-and-spruce-spider-mites/))
• Dry conditions and drought stress can encourage outbreaks and make trees less able to tolerate feeding. ([ipm.ucanr.edu](https://ipm.ucanr.edu/home-and-landscape/pine-and-spruce-spider-mites/))
• Broad-spectrum insecticides can kill natural mite predators and make an outbreak worse. ([extension.colostate.edu](https://extension.colostate.edu/resource/spider-mites/))

How to tell it apart

Hold white paper beneath a suspect branch and tap the branch firmly. Repeat at three or four places around the tree, looking for tiny, dark, oval specks walking across the paper; a magnifying lens helps. Moving mites together with speckled needles and fine silk support the diagnosis—webbing alone does not confirm it. ([extension.psu.edu](https://extension.psu.edu/spruce-spider-mite?utm_source=openai))

Ordinary spider webs

Spider silk can be mistaken for mite webbing. Check the needles for feeding speckles and use the white-paper test rather than treating because you see a web. ([extension.colostate.edu](https://extension.colostate.edu/resource/spider-mites/))

Spruce needle miners

These make small nests of brown needles webbed against a branch. Affected needles are hollow, with a small hole near the base. ([apps.extension.umn.edu](https://apps.extension.umn.edu/garden/diagnose/plant/evergreen/spruce/needlesdiscolored.html))

Rhizosphaera needle cast

Older needles turn brown or purplish while branch tips stay green. Look with a hand lens for tiny black dots on affected needles, often starting on lower branches. ([apps.extension.umn.edu](https://apps.extension.umn.edu/garden/diagnose/plant/evergreen/spruce/needlesdiscolored.html))

Winter injury

Browning appears in late winter or early spring, often on one exposed side. Needle tips brown first while their bases may remain green. ([apps.extension.umn.edu](https://apps.extension.umn.edu/garden/diagnose/plant/evergreen/spruce/needlesdiscolored.html))

Treatment

1. Confirm that mites are still active Do the white-paper test this week before buying a spray. Old damage can remain after mites disappear. If you find eggs but no moving mites in fall, arrange a spring recheck rather than automatically spraying now. ([hort.extension.wisc.edu](https://hort.extension.wisc.edu/articles/spruce-spider-mite/))
2. Wash reachable foliage thoroughly If live mites are present, direct a strong hose spray into the inner branches, not just the outer tips. Start this week and repeat three times a week for two weeks; dense spruce growth can shelter mites from the water. ([hnr.k-state.edu](https://hnr.k-state.edu/extension/horticulture-resource-center/common-pest-problems/documents/Spruce%20Spider%20Mite.pdf))
3. Recheck before escalating Repeat the paper test after the washing course. If mites remain abundant, ask your local extension service about a selective miticide labeled for spruce and spider mites. Cover inner foliage thoroughly and follow the label for dilution, weather limits and repeat timing; keep the product and spray away from pets and children. ([hnr.k-state.edu](https://hnr.k-state.edu/extension/horticulture-resource-center/common-pest-problems/documents/Spruce%20Spider%20Mite.pdf))
4. Avoid choosing an oil spray without checking suitability Sources differ: University of California guidance allows horticultural oil but warns it can remove blue spruce's blue color; Kansas State advises against oils on spruce because of injury risk, especially on dwarf Alberta spruce. Ask extension about your particular spruce before using oil. If recommended, follow the label and keep it away from pets and children. ([ipm.ucanr.edu](https://ipm.ucanr.edu/home-and-landscape/pine-and-spruce-spider-mites/))

Prevention

• Check susceptible spruces with the white-paper test during spring and fall, when this mite is usually most active. ([ipm.ucanr.edu](https://ipm.ucanr.edu/home-and-landscape/pine-and-spruce-spider-mites/))
• Maintain appropriate irrigation during dry weather to reduce drought stress. ([extension.colostate.edu](https://extension.colostate.edu/resource/spider-mites/))
• Avoid unnecessary nitrogen fertilizer and broad-spectrum insecticides, which can favor mite outbreaks. ([ipm.ucanr.edu](https://ipm.ucanr.edu/home-and-landscape/pine-and-spruce-spider-mites/))

When to worry

Seek extension help if browning is widespread, needles are dropping heavily, or you cannot confirm the cause. Sources describe severity differently: UC says damage is usually less serious than it looks, while Wisconsin warns that heavy infestations cause browning and premature needle loss. Judge urgency by live mite numbers and continuing damage, not webbing alone. ([ipm.ucanr.edu](https://ipm.ucanr.edu/home-and-landscape/pine-and-spruce-spider-mites/))

Safety

For any miticide or horticultural oil, follow the label, including protective clothing, application restrictions and instructions for keeping people and animals away. Handle carefully and store in the original labeled container out of reach of pets and children; prevent contamination of ponds and streams. ([extension.psu.edu](https://extension.psu.edu/spruce-spider-mite?utm_source=openai))

Sharing your home with pets or small children? See which plants our sources call safe for cats, dogs and kids.

FAQ

Will the brown needles turn green again?

No. Damaged needles do not recover after mites are gone; treatment protects the remaining healthy foliage. ([hort.extension.wisc.edu](https://hort.extension.wisc.edu/articles/spruce-spider-mite/))

Can water alone control spruce spider mites?

Sometimes. Kansas State recommends a strong water spray three times weekly for two weeks, reaching inside the dense branches. ([hnr.k-state.edu](https://hnr.k-state.edu/extension/horticulture-resource-center/common-pest-problems/documents/Spruce%20Spider%20Mite.pdf))

Should I spray in November?

Not just because it is November. Check for live mites first; if only overwintering eggs are found in fall, Wisconsin recommends checking again in spring for activity. ([hort.extension.wisc.edu](https://hort.extension.wisc.edu/articles/spruce-spider-mite/))

Will an ordinary insect spray work?

Many insecticides do not control mites, and some worsen outbreaks by killing their predators. Do not use one by default. ([extension.colostate.edu](https://extension.colostate.edu/resource/spider-mites/))

Sources

• University of Minnesota Extension: Spruce—Discolored needles
• Penn State Extension: Spruce Spider Mite
• Kansas State Research and Extension: Spruce Spider Mite
• Colorado State University Extension: Spider Mites
• UC Statewide IPM Program: Pine and Spruce Spider Mites
• University of Wisconsin Extension: Spruce Spider Mite
• Spruce Spider Mite