Ficus benjamina pests: scale, spider mite and mealybug told apart

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Three pests account for almost every infested weeping fig indoors, and all three are encouraged by the same thing: warm, dry, still air. A plant standing near a radiator through the heating months is the classic case.

The damage they cause looks similar — leaves dulling, yellowing, then falling — which is why the plant is often treated for the wrong problem, or watered more in the belief that it is thirsty.

Identifying the three

• Scale insects — small brown or fawn limpet-like bumps, 2 to 5 mm, on stems and along leaf veins. They do not move. Scrape one with a fingernail and it lifts off, leaving a soft body beneath
• Red spider mite — almost invisible individually. What you see is fine webbing between leaves and stem, and a dull bronze speckling on the upper leaf surface. Hold a sheet of white paper under a shaken leaf: moving specks confirm it
• Mealybugs — white cottony tufts in leaf axils and where stems fork. Unmistakable once seen, and often mistaken for mould at first

All three suck sap, and all three leave honeydew: a sticky shine on leaves, on the floor, on the furniture below. That stickiness is usually the first thing anyone notices.

Why they arrive, and why the same plant is hit twice

• Dry air. Heated rooms suit spider mite perfectly and suit the plant badly. Humidity is the single most useful preventive measure
• A new plant brought home untreated. Most infestations arrive with a purchase; two weeks apart from the collection would have caught them
• Still air. A plant in a corner with no movement is a plant nobody inspects and nothing disturbs
• Overfeeding. Soft nitrogen-rich growth is easier to pierce than firm growth

Treating each one

• Scale: wipe each one off with a cloth or a cotton bud dipped in soapy water. Tedious but decisive, since the adults do not move. Repeat weekly for a month to catch the crawlers as they hatch. Details on scale insects and how to treat them
• Spider mite: raise humidity immediately, shower the whole plant including leaf undersides, then treat every five to seven days for three weeks. One treatment achieves nothing because eggs are untouched. See red spider mite and its organic treatments
• Mealybug: touch each cluster with a cotton bud dipped in alcohol, then rinse. Check the leaf axils and the compost surface, where they hide

Whatever the pest, isolate the plant before treating and check its neighbours. An infestation found on one plant is rarely on one plant only.

What not to do

• Do not water more because the leaves look poor. It is the commonest reflex and it adds root rot to the pest problem — see the seven causes of leaf drop
• Do not spray the top surface only. Mites and scale live underneath; a treatment applied from above misses them
• Do not treat once and stop. Every one of these pests has an egg stage that no treatment reaches. Three passes at weekly intervals is the minimum
• Do not feed a struggling plant. Soft growth is exactly what the pest wants
• Do not repot to fix it. The problem is above the compost

Preventing the next one

• Stand the pot on a tray of moist gravel, or group plants, to hold humidity around the foliage
• Keep the plant away from radiators and away from cold draughts alike
• Wipe the leaves every few weeks. It removes early colonies and forces you to look at the undersides
• Quarantine every new plant for two weeks before it joins the others
• Take cuttings from healthy growth if a badly infested specimen has to be cut back hard

For the growing method, see the weeping fig care guide. The same pests and the same treatments apply to the fiddle-leaf fig and to Ficus microcarpa.