Why does my fiddle-leaf fig have fine webbing between the leaves?

On a fiddle-leaf fig this is a fine, silvery web between a leaf and the stem or across the underside of a leaf, with pale speckling on the leaf above it where the mites have fed. The leaves look dull.

The most likely cause is spider mites, as the entry says, and the plant is a common target. The Royal Horticultural Society names red spider mite as a pest of ornamental figs under glass, and the Missouri Botanical Garden lists spider mites for this plant. Mites breed fast in warm, dry air and slowly in damp air, and a heated room in winter suits them. Medium humidity is what this plant is meant to live in, and a dry, heated room is where they take hold.

To confirm it in a minute, hold a sheet of white paper under a leaf and tap it. Spider mites fall as specks the size of a full stop and then walk, which dust does not. Turn the leaf over and look along the veins on the underside, and look where the leaf joins the stem. A magnifying glass makes the specks clear.

Two other causes are worth ruling out. A plant bought or given in the last month may have brought them in, and the plants beside it will begin to speckle. Other sap suckers, the NC State plant toolbox says, include scale, aphids, mealybugs and thrips, and scale and mealybug leave a sticky residue where mites leave a web.

Speckled leaves stay speckled, so judge the recovery by the new growth and by the webbing, which should stop reappearing within a few weeks of washing and better humidity. Mites run through a generation quickly, and the page on fine webbing gives the routine that covers it.

What this plant wants

The fix

Wipe both sides of every leaf, raise the humidity around the plant, and treat weekly with an insecticidal soap until the webbing stops appearing.

Read on

Fine webbing between the leaves

The same sign on any plant, with the causes in the order they are likely.

Fiddle-leaf fig care

Light, water, feeding, repotting and the rest of the entry.

Check it in the diagnoser

Opens with the plant, the part and the sign already chosen.