Spider Mites: Causes, Diagnosis & Fixes
Spider mites are tiny arachnids that suck plant sap, causing stippled, discolored leaves. They thrive in warm, dry conditions and can multiply rapidly.
Quick diagnosis
Spider mites are persistent but manageable. Increase humidity, treat consistently over several weeks, and inspect regularly to prevent reinfestations.
考えられる原因
Low Humidity / Dry Air
Why: Spider mites prefer dry conditions and populations explode in low-humidity environments.
Signs to check: Problem is worst during winter with indoor heating, other plants nearby may also be affected.
Warm Indoor Temperatures
Why: Warm conditions speed up spider mite reproduction cycles, leading to rapid population growth.
Signs to check: Plant is in a warm room, mite damage progresses quickly over days to weeks.
Introduction from New Plants
Why: Spider mites can hitchhike on new plants brought into the home.
Signs to check: Problem started after adding a new plant, mites found on the newcomer as well.
確認ポイント
- 1Look for fine webbing on leaf undersides and between stems
- 2Hold a white paper under a leaf and tap — look for tiny moving specks
- 3Check for stippled or speckled discoloration on leaf surfaces
- 4Inspect all nearby plants as mites spread easily
対処法
- Isolate the affected plant immediately
- Spray the entire plant with a strong stream of water to dislodge mites
- Increase humidity around the plant — mites dislike moist conditions
- Apply insecticidal soap or neem oil, covering undersides of all leaves
- Repeat treatment every 5-7 days for at least 3-4 weeks to break the lifecycle
専門家に相談するタイミング
- Heavy webbing covering large portions of the plant
- Leaves are turning brown and falling off rapidly
- Mites have spread to multiple plants despite treatment
ポイント
Spider mites are persistent but manageable. Increase humidity, treat consistently over several weeks, and inspect regularly to prevent reinfestations.
Frequently asked questions
What causes spider mites in houseplants?
Spider mites are tiny arachnids that suck plant sap, causing stippled, discolored leaves. They thrive in warm, dry conditions and can multiply rapidly. Common causes include low humidity / dry air, warm indoor temperatures, introduction from new plants.
How do I fix spider mites?
Start by identifying the likely cause instead of applying every remedy at once. Isolate the affected plant immediately Spray the entire plant with a strong stream of water to dislodge mites Increase humidity around the plant — mites dislike moist conditions
Track the problem over time
アプリで回復を追跡
進捗を記録し、リマインダーを設定し、AI による診断を受けましょう。
Sources and review
Content last reviewed: September 4, 2026
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