Spider Mites on Houseplants: Identify, Prevent, and Manage

Spider mites are tiny — easy to miss until you see the damage. Getting on top of them early is straightforward, and the conditions they thrive in are the real lever: extension horticulture confirms dry indoor air and reduced plant vigour favour the mites (Iowa State Extension).

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How to identify spider mites

Look for these together:

• Stippling — leaves “speckled with very tiny yellowish-green spots” (Iowa State Extension).
• Discolouration — over time leaves turn greenish-yellow, then tan or brown (Iowa State Extension).
• Fine webbing on leaves and stems is a strong confirmation (Iowa State Extension).

You’ll usually see damage and webbing before the mites themselves. Inspect both leaf surfaces.

Why they’re here — the conditions

Spider mites flourish in dry indoor air on stressed plants (Iowa State Extension). Heated rooms and dry vents are classic triggers — treating conditions matters as much as treating mites.

Prevention-first management

1. Isolate the affected plant.
2. Rinse the foliage with water — extension: “washing or syringing infested plant foliage may reduce light mite populations” (Iowa State Extension). Lukewarm, both surfaces, in the shower/sink.
3. Raise local humidity (group plants, humidifier, pebble tray) — mites prefer dry air.
4. Insecticidal soap when rinsing isn’t enough; commercial insecticidal soap is preferred (avoid dishwashing detergent) (Iowa State Extension). Treatments commonly need to be repeated because of the mites’ life cycle.

When a plant is too far gone

If heavily webbed and severely stippled, the kindest realistic move is to discard the plant and protect the rest of the collection — propagate a clean cutting where feasible. Honest beats nursing a hopeless case while it seeds your shelf.

Stop it coming back

Quarantine new plants for a couple of weeks. Keep plants healthy: right light, correct watering. Manage room humidity in winter.

Related: Why Are My Plant Leaves Curling? (mites are one cause), the Troubleshooting hub, and Plant Care Basics.