Spider Mites on Houseplants
Spider mites (Tetranychus urticae) are tiny arachnids that pierce leaf cells and feed on the contents, leaving a stippled or sandblasted look on foliage. Webbing along leaf undersides is a tell-tale sign of an established infestation. They thrive in warm, dry conditions — typical indoor air in winter.
How to identify spider mites
Adult mites are about 0.4 mm long, oval, and pale yellow to red. Easier to spot than the mites themselves: fine silk webbing on leaf undersides and the petiole, plus tiny pale dots on the upper leaf surface where chlorophyll has been depleted.
Damage to look for
Stippled or sandblasted yellow-to-bronze speckling on leaves, fine webbing on leaf undersides and where petioles meet stems, leaves yellowing and dropping, slowed growth.
Life cycle (why they spread so fast)
Egg to adult in 5–20 days depending on temperature; populations explode at 80°F+ and low humidity. A single female lays ~100 eggs over her ~30-day life.
How to get rid of spider mites
- Rinse the plant in a shower or with a strong stream of water to dislodge mites and webbing.
- Spray all leaf surfaces (especially undersides) with insecticidal soap or a 1% horticultural oil solution, repeat every 5–7 days for 3–4 cycles to break the life cycle.
- For heavy infestations, isolate the plant from other plants for at least 3 weeks.
- In persistent cases, switch to a different miticide class (e.g. abamectin per label) to avoid resistance.
How to prevent spider mites
- Maintain 50%+ humidity — spider mites struggle above 60% RH.
- Inspect new plants for 2–3 weeks before mixing with the rest of your collection.
- Wipe leaves down monthly to disrupt early colonies.
Per-species treatment guides
Treatment varies slightly by plant. Find your species below for a dedicated guide.
Source: UC IPM — Spider Mites