Mealybugs, spider mites, aphids: how to spot and treat houseplant pests

A sticky plant, little white tufts, fine webs under the leaves? Houseplant pests are few, and they can be treated with simple means, as long as you spot them early and stay patient.

Updated on 9 October 2026

Mealybugs

How to spot them: small white, cottony tufts where leaves meet stems, along the veins or at the heart of the plant. The leaves become sticky, and sometimes get covered in a fine black dust, sooty mould, a fungus that feeds on the honeydew they excrete.

What to do: remove each tuft with a cotton bud dipped in 70% rubbing alcohol, then spray the whole plant with soapy water (recipe below). Check the roots at the next watering too: some mealybugs hide there. Succulents and orchids are among their favourite targets.

Scale insects

How to spot them: small brown or beige bumps 2–5 mm across, motionless, stuck to stems and under leaves. They're often mistaken for part of the plant. The leaves get sticky, as with mealybugs.

What to do: their shell protects them from sprays. Pick them off one by one with a fingernail, an old toothbrush or a cotton pad dipped in alcohol, then clean the leaves with soapy water. Ficus, palms and citrus are prone to them.

Spider mites

How to spot them: they're almost invisible to the naked eye. What you see is the damage: dull leaves speckled with tiny yellow dots, then fine webs under the leaves and between stems. They love warm, dry air: they're the winter pest, when the heating is on.

What to do: shower the plant with lukewarm water, focusing on the undersides of the leaves, then raise the humidity around it (a tray of wet clay pebbles, plants grouped together). Treat with soapy water every week. For a heavy infestation, predatory mites (Phytoseiulus persimilis), sold in garden centres, do a remarkable job. Crotons, calatheas and palms are frequent targets.

Aphids

How to spot them: small green, black or white insects, clustered in colonies on young shoots and flower buds, which become distorted. They often come in from outdoors, in spring and summer.

What to do: a jet of water is often enough to dislodge them. Otherwise, spray with soapy water. Avoid too much fertiliser, which produces the soft growth they love.

Thrips and whitefly

Thrips leave silvery streaks on the leaves, dotted with tiny black specks. The insects themselves are tiny and slender. Shower the plant, treat with soapy water, and put up a blue sticky trap: they're stubborn pests that need consistency.

Whitefly rise in a cloud when you touch the plant. A yellow sticky trap catches the adults, and soapy water under the leaves deals with the larvae.

The soapy water recipe

Mix one tablespoon (15 ml) of pure liquid soft soap (potassium soap, with no additives) into a litre (about a quart) of lukewarm water. Spray the tops and especially the undersides of the leaves, and the stems, out of direct sun.

• Test on one leaf first, and wait a day or two before treating the whole plant.
• Repeat every week, three or four times: eggs hatch after the first treatment.
• Avoid fuzzy leaves, like those of the African violet, and succulents with a powdery coating: for them, a cotton bud dipped in alcohol, case by case, is gentler.

Prevention beats cure

• Check every plant when you buy it, and keep it away from the others for two weeks.
• Dust the leaves now and then: it's a chance to spot intruders early.
• Avoid air that's too dry in winter, which favours spider mites.
• A well-placed plant, neither drowned nor thirsty, resists much better.

And if a small plant is infested all over, it's sometimes wiser to part with it than to risk infecting the others. For the little flies buzzing around the soil, that's a different problem: see the fungus gnats guide.

This advice is for houseplants in a temperate climate. Every home is different: trust your plant too, and the soil under your finger.