Spider Mites: How to Get Rid of Them (and Prevent Them)
Identify and eliminate spider mites: fine webbing, yellow stippling and drying leaves. Step-by-step treatment with water, soap and humidity, and prevention.
In this article
Spider mites are one of the most annoying and stealthy pests: by the time you see the webbing, there's already a large colony. They're not insects but tiny mites that suck sap and thrive in heat and dry air. I've had to deal with them more than once, especially in winter with the heating on, and I learned the battle is won with two things: humidity and persistence.
How to identify them
| Sign | Detail |
|---|---|
| Yellow or silvery stippling | Like tiny pinpricks on the face of the leaf |
| Very fine webbing | On undersides and between stems (advanced sign) |
| Dull, dry leaves that drop | The plant loses vigor |
| Tiny red/brown dots moving | On the undersides; visible with a loupe |
Foolproof trick: hold a white sheet of paper under a leaf and tap it. If you see tiny moving dots on the paper, it's spider mites.
Why they appear
They love hot, dry conditions: heating in winter, heat spells in summer. That's why they attack mostly indoors and on plants stressed by underwatering. Humidity-loving plants like the calathea are their favorite victims when the air dries out.
Step-by-step treatment
- Isolate the plant: spider mites jump easily to neighbors.
- Pressure rinse: wash the whole plant, focusing on the undersides, to wash away mites and webbing. It knocks the population down fast.
- Spray with insecticidal soap (or neem oil), covering the undersides really well. Repeat every 4-5 days for 3 weeks: this is the most important part, because it breaks the cycle of eggs as they hatch.
- Raise humidity: mist often or use a humidifier.
Why humidity is your best weapon
Spider mites hate humidity: they thrive precisely when the air is dry. Raising ambient humidity (with a humidifier, by grouping plants, or with a pebble tray of water) makes the environment hostile to them and strengthens the plant. It's the best long-term prevention; details in the humidity guide.
How to prevent a comeback
- Keep ambient humidity high, especially in winter with heating.
- Check leaf undersides weekly when you water; cleaning leaves helps you spot them early.
- Quarantine new plants for 1-2 weeks.
- Don't let plants go thirsty: a stressed plant is more vulnerable.
When to worry
If the plant is heavily infested and weak, prune the worst leaves (those covered in webbing) and repeat the treatment on the healthy parts. On valuable plants or in a greenhouse, predatory mites (Phytoseiulus persimilis) are a very effective biological control.
Spider mites or another pest?
Don't confuse them: mealybugs leave cottony specks; thrips leave silvering but with tiny black dots (their droppings) and no webbing. The fine webbing is the unmistakable signature of spider mites.
Persistence wins the battle: don't quit at the first improvement, because the eggs keep hatching. Not sure it's spider mites? Upload a photo to the AI diagnosis tool.
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