Webbing on Houseplant Leaves — Spider Mites and How to Kill Them

Photo: Gilles San Martin, CC BY-SA 2.0, via Wikimedia Commons

Fine webbing where the leaf meets the stem, plus leaves that look faded and dusty, means spider mites. They are arachnids, not insects, which is why ordinary bug sprays often fail against them.

Confirming it

Hold a sheet of white paper under a leaf and tap sharply. Spider mites fall off as moving specks the size of a full stop, red, orange or pale green. On the leaf itself, look for stippling — thousands of tiny pale dots where each mite has emptied a cell. Dust does not move and does not stipple.

Why they appear in winter

Spider mites need warmth and dry air, so the moment the heating goes on they multiply — a generation can complete in under a week at 27°C. Plants that sailed through summer outdoors often collapse indoors in November for exactly this reason.

Treatment that works

1. Isolate the plant immediately. Mites walk, and they will be on the neighbours within days.
2. Rinse it. Take it to the shower or sink and wash both leaf surfaces with lukewarm water. This physically removes most of the population, which no spray does as well.
3. Treat with horticultural oil or insecticidal soap, covering the leaf undersides thoroughly — that is where they live. Repeat every five days.
4. Keep repeating for three weeks. Eggs are unaffected by most treatments, so a single application simply resets the clock on the next generation.

Prevention

Raise the humidity — grouping plants, a pebble tray, or moving them away from radiators all help, because mites struggle above roughly 60% humidity. Inspect new plants before they join the shelf, and check the undersides of anything that comes indoors for winter.

Not sure that's what you have?

Symptoms overlap, and the wrong treatment wastes weeks. Photograph the affected leaf with Sherleaf and you get the diagnosis, a severity rating and a treatment plan in about ten seconds.