Fine webbing and speckled leaves: spider mites
Spider mites are tiny, barely visible pests that feed on leaf undersides in warm, dry indoor air. The signs are fine speckling or bronzing on leaves, a dusty feel under the leaf, and delicate webbing where leaves meet stems.
They are not insects, so treatments aimed at ordinary insects do not reliably control them. They also multiply fast in dry air, which is why the first steps are physical: rinse, raise humidity around the plant, and isolate it.
General beginner information only — not a substitute for advice from your local agricultural extension service. For edible plants, use only a product that is labelled for that particular edible crop, for indoor use, and follow any harvest interval on its label; try non-chemical steps first, and never use a product that is not labelled for indoor use on that plant.
Checklist to diagnose
- Are leaves speckled with tiny pale dots, bronzed, or dusty-looking, especially from below?
- Is there fine webbing at leaf joints or across leaf undersides?
- Shake a leaf gently over white paper: do tiny moving dots fall off?
- Is the air warm and dry, and is the plant near a heat source?
- Are neighbouring plants showing the same speckling?
Rescue steps
- Isolate the plant and rinse the foliage thoroughly, including the undersides, in a shower or sink; repeat the rinse every few days for a week or more.
- Raise the humidity around the plant — set the pot on a tray of damp pebbles with the pot base above the water, keeping the plant isolated — and move it away from dry heat.
- Remove the most damaged leaves with clean scissors if the plant can spare them.
- If rinsing and humidity do not stop the spread, use a product labelled for spider mites for indoor use on that plant, follow its label exactly, and repeat only as the label directs, since new mites keep hatching.
- Keep checking leaf undersides weekly after the plant looks clean; mites return quickly in dry air.
When to give up
- Leaves are mostly bronzed and dry, webbing covers the plant, and new growth is attacked as fast as it appears despite rinsing and treatment.
Plants on this site
This page gives general indoor advice: it applies to indoor-grown plants generally and is not a claim about any particular plant on this site.