Spider mites — too small to see, hard to miss
Spider mites are tiny pests — about 0.4mm — that thrive in hot, dry conditions. Because they are so small you will rarely see the pests themselves; the first signs are usually the damage they cause, or the fine webbing they produce to protect their colonies.
What to look out for
- Fine webbing — Look for delicate, silky webs in the joints of the plant — where the leaf meets the stem — or across the undersides of leaves. This is often the most obvious sign of a spider mite infestation.
- Stippling on leaves — Spider mites feed by sucking chlorophyll from individual plant cells. That leaves tiny pale yellow or white dots across the leaves, giving the foliage a washed-out, speckled, or dusty appearance.
- Dusty or gritty undersides — If the underside of a leaf feels gritty or dusty, the particles may actually be mites and their eggs clustered along the veins.
- The 'white paper' test — Hold a sheet of white paper under a leaf and give the leaf a firm tap. If tiny moving specks fall onto the paper and begin crawling, it is a strong sign of spider mites.
Examples of spider mites in real homes
Why they’re difficult to eliminate
Spider mites reproduce extremely quickly. A single female can lay hundreds of eggs, and in warm indoor environments those eggs can hatch and reach adulthood in as little as 5–7 days. Because of this rapid life cycle, infestations escalate quickly if not treated consistently.
How to treat them
- Isolate immediately — Move the affected plant to a separate room to stop the infestation spreading to other plants.
- Rinse the plant — Take it to the sink or shower and use a steady stream of water to wash away as many pests as possible. This removes a large portion of the mites and breaks apart their protective webbing.
- Prune heavily infested areas — Remove heavily infested leaves or stems with clean scissors and dispose of them immediately.
- Use an insecticide — Apply an insecticide thoroughly across the entire plant, including the stems and the undersides of leaves. Repeat weekly for about 5 weeks to break the pest life cycle.
- Increase humidity — Spider mites thrive in hot, dry air. Raising humidity with a humidifier helps slow their reproduction — though it will not eliminate them on its own.
- Introduce a biological control — For larger plant collections, introduce beneficial insects such as predatory mites (Phytoseiulus persimilis). These natural predators feed on spider mites, then die off once the food source is gone.