Eriophyid mite

Eriophyidae (family)

54 host plants

Last updated

Eriophyid mites are microscopic arachnids that feed on pine, fir, and other conifer foliage, causing discoloration, distortion, and abnormal growth of needles. You will see affected needles appear stunted, curled, or develop unusual coloring without visible pest activity. Damage accumulates on new growth in spring and early summer. Heavy infestations can reduce tree vigor and cause branch dieback.

Most trees tolerate eriophyid mite damage without serious decline. No effective chemical control is practical for landscape trees. Maintain tree vigor through adequate watering and avoid drought stress that makes plants more susceptible. Prune out severely affected branches if damage is severe. Natural predatory mites and other beneficial arthropods usually keep eriophyid mite populations in balance without intervention.

Quick Reference

Order
Trombidiformes
Type
mite
Host Plants
54
Peak Activity
March-May: Emergence from bud scales as buds swell; gall initiation begins on...
Damage Severity
cosmetic
Now: Active Feeding & Gall FormationModerate Risk

Multiple overlapping generations develop on foliage. Erineum patches, leaf blisters, and galls expand and mature. Damage is primarily cosmetic on landscape hosts. Once galls are fully formed, mites inside are protected from contact treatments.

Next: Fall Migration to Buds

Monitoring & Action

How to Monitor

Dormant season: Inspect buds and bark crevices for overwintering populations (low priority for cosmetic damage). March-May: Scout for early gall formation on new growth and expanding leaves. Once galls are visible and fully formed, mites are protected inside tissue and contact treatments are ineffective. Diagnosis is by symptom: blisters, erineum patches, galls, or russeting on specific hosts.

When to Act

For most landscape plants: no action threshold. Galls and erineum are cosmetic and plant health is unaffected. Exceptions: (1) Fuchsia gall mite (Aculops fuchsiae) causes severe branch deformation on show plants and warrants management. (2) Rust mites on commercial fruit crops may affect marketability. For ornamental landscape plants, accept the damage.

What Damage Looks Like

Damage varies by mite species and host but falls into four general categories: (1) Leaf blisters - raised, discolored bumps on upper or lower leaf surface (pearleaf blister mite on pear, maple bladdergall mite on Acer); (2) Erineum patches - dense felty mats of abnormal plant hairs on leaf undersides, often white, pink, or red (erineum mites on maple, linden, alder); (3) Galls - swollen, deformed buds, flowers, or stems (ash flower gall on Fraxinus, fuchsia gall mite on Fuchsia); (4) Russeting/bronzing - surface discoloration without galling (rust mites on fruit crops). Most damage is cosmetic on landscape plants. Plant vigor is rarely affected. Galls are the plant's defensive response to mite feeding, not structures built by the mite.

Cultural Controls

  • Accept cosmetic damage on landscape plants. Galls, blisters, and erineum patches do not harm plant health. No treatment is necessary for the vast majority of landscape hosts.
  • For fuchsia gall mite (Aculops fuchsiae): prune heavily infested growth aggressively and dispose of prunings. Choose resistant cultivars (species fuchsias more resistant than hybrids).
  • Avoid overhead irrigation that creates humid microclimates favorable to mite populations.

Host Plants (54)

Agathis australis Kauri Tāne Mahuta, Kauri Pine Araucaria araucana Monkey Puzzle Tree, Chilean Pine Araucaria bidwillii Bunya Pine Araucaria cunninghamii Hoop Pine, Moreton Bay Pine Araucaria heterophylla Norfolk Island Pine Athrotaxis laxifolia Tasmanian Pencil Pine, Summit Cedar Cephalotaxus harringtonia Japanese Plum Yew, Cow's Tail Pine Glyptostrobus pensilis Chinese Swamp Cypress, Water Pine Water Fir Shui song Microcachrys tetragona Creeping Pine, Creeping Strawberry Pine Pinus albicaulis Whitebark Pine, Scrub Pine, White Pine Pinus aristata Bristlecone Pine, Rocky Mountain Bristlecone Interior Bristlecone Pinus attenuata Knobcone Pine Pinus banksiana Jack Pine, Scrub Pine, Banksian Pine, Hudson Bay Pine Pinus bungeana Lacebark Pine, Whitebark Pine, Baipi Song Pinus canariensis Canary Island Pine Pinus cembra Swiss Stone Pine Pinus contorta Lodgepole Pine Pinus contorta var. contorta Shore Pine Pinus contorta var. latifolia Rocky Mountain Lodgepole Pine Pinus coulteri Coulter Pine, Bigcone Pine Pinus densiflora Japanese Red Pine Pinus edulis Pinyon Pine, Piñón Pine, Two-needle Pinyon Colorado Pinyon Pinus elliottii Slash Pine, Swamp Pine Pinus flexilis Limber Pine, Rocky Mountain White Pine Pinus halepensis Aleppo Pine, Jerusalem Pine Pinus heldreichii Bosnian Pine, Snakeskin Pine Pinus jeffreyi Jeffrey Pine, Western Yellow Pine, Bull Pine Pinus kwangtungensis Kwangtung Pine, Guangdong Pine Pinus lambertiana Sugar Pine Pinus leucodermis Bosnian Pine Pinus monophylla Singleleaf Pinon Pine, One-leaved Pine Pinus monticola Western White Pine Pinus mugo Mugo Pine Pinus mugo var. pumilio Mugo pine, Dwarf Mugo pine Pinus nigra Austrian Pine Pinus parviflora Japanese White Pine Pinus parvifola Pinus parvifola Pinus pinaster Maritime Pine, Cluster Pine, Turpentine Pine Pinus pinea Italian Stone Pine, Umbrella Pine Pinus ponderosa Ponderosa Pine, Western Yellow Pine Pinus pumila Japanese Stone Pine, Dwarf Siberian Pine Pinus radiata Monterey Pine Pinus resinosa Red Pine Pinus sabiniana Gray Pine, Foothill Pine Pinus strobiformis Southwestern White Pine, Mexican White Pine, Chihuahua White Pine Pinus strobus Eastern White Pine Pinus sylvestris Scots Pine, Scotch Pine Pinus thunbergii Japanese Black Pine Pinus virginiana Virginia Pine, Scrub Pine, Jersey Pine Pinus wallichiana Himalayan Pine, Bhutan Pine Pinus yunnanensis Yunnan Pine Pyrus communis Common Pear Sciadopitys verticillata Japanese Umbrella Pine, Umbrella Pine Wollemia nobilis Wollemi Pine

Eriophyid mites are ubiquitous in the Puget Sound lowlands. Maple bladdergall mite on silver and red maples is the most commonly noticed species. Pearleaf blister mite is common on ornamental pears. The cool, moist maritime climate may moderate population buildup compared to hotter inland regions. For landscape settings, the standard advice applies: accept the cosmetic damage. Fuchsia gall mite has been increasingly reported on garden fuchsias in the region.

— Chris Welch, ISA Certified Arborist

Sources & References

Primary: PNW Insect Management Handbook

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