Gall Mites
Eriophyidae
📖 Description
Gall mites, also known as eriophyid mites, are microscopic mites that cause distinctive abnormal growths (galls) on plants by feeding on tender tissue and injecting growth-regulating chemicals. These galls take many forms depending on the mite species and host plant, including bladder galls on maples, erineum galls with felt-like patches, and bud galls that distort new growth. While the galls are often unsightly, they rarely cause serious harm to the overall health of the plant. Gall mites are highly host-specific, with each species typically affecting only one or a few closely related plant species. Their microscopic size means they are identified by the galls they produce rather than by direct observation.
⚠️ Symptoms to watch for
- Distinctive galls or growths on leaves, buds, or stems,Maple bladder galls — green or red bumps on upper leaf surfaces,Fuchsia gall — swollen, distorted growth at shoot tips,Citrus bud mite — distorted, rosetted new growth,Erineum galls — felt-like patches on leaf undersides,Stunted or deformed new growth on affected branches
🩹 Treatment
- Prune and destroy affected plant parts (organic),Apply horticultural oil during dormant season (organic),Spray with wettable sulfur during bud break (organic),Remove and destroy heavily infested branches (organic),Apply abamectin spray (chemical),Use carbaryl spray during bud break (chemical)
🌿 Organic treatments
- Prune and destroy affected plant parts,Apply horticultural oil during dormant season,Spray with wettable sulfur during bud break,Remove and destroy heavily infested branches
🧪 Chemical treatments
- Apply abamectin spray,Use carbaryl spray during bud break
🛡️ Prevention
- Inspect new plants for galls before purchasing or planting,Prune out galled growth before mite populations build,Apply dormant horticultural oil in late winter,Maintain plant health with proper watering and fertilization,Remove and destroy fallen leaves that may harbor overwintering mites,Avoid excessive nitrogen fertilization that promotes succulent growth
🪴 Affected plants
- Maples,Fuchsias,Citrus,Various Trees and Shrubs
🦋 Natural predators
- Predatory Mites,Ladybugs
🌱 Host plants
- Acer spp.,Vitis spp.,Prunus spp.
🔄 Lifecycle
- Overwintering females shelter in bud scales, bark crevices, or under galls.
- In spring, they emerge and begin feeding on newly expanding tissue, inducing gall formation.
- They reproduce within the galls, with females laying 50-80 eggs.
- Development from egg to adult takes 1-2 weeks.
- Multiple overlapping generations occur within the galls throughout the growing season.
- In fall, mites move to overwintering sites.
- Some species are vectored by wind or insects to new host plants.
📅 Season
- Spring to Fall (gall formation begins at bud break)
🔎 Appearance
- Microscopic, worm-like or cigar-shaped mites with only two pairs of legs near the head, unlike other mites which have four pairs.
- Invisible to the naked eye.
- Their presence is detected by the distinctive galls (abnormal growths) they cause on leaves, buds, and stems.
💥 Damage level
- Low
🔁 Reproduction rate
- Moderate
🗺️ Geographic regions
- North America
- Europe
- Asia
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