Scale Insects
Sap-sucking insects that disguise themselves as small, hard brown bumps stuck along stems and leaves.
🔍 How to spot it
Scale look less like insects and more like small, waxy bumps - brown, tan or grey, oval and limpet-shaped - firmly attached to stems, leaf veins and undersides. They do not move once settled. Sticky honeydew and sooty mould below the plant often reveal them before the bumps are noticed.
💥 The damage it does
They tap into the sap stream and drain it, causing yellowing, poor growth and, in heavy infestations, dieback. Like mealybugs they produce honeydew that leads to sticky leaves and black mould, and their hard shell makes them stubborn to shift.
🧴 How to treat it
Scrape or rub scale off with a fingernail, an old toothbrush or a cotton bud soaked in rubbing alcohol - the protective shell means sprays alone often fail. Follow with horticultural oil, which smothers them, repeated weekly until no new bumps appear. Prune out badly encrusted stems.
🛡️ How to prevent it
Check new plants and quarantine them, since scale spread slowly and often arrive hidden on a single stem. Inspect stems and leaf undersides during routine care, and treat the first few before they colonise the whole plant.
🌿 Plants that get scale insects
Common on woody-stemmed houseplants, ficus, citrus and ferns. These 82 profiled plants name them in their own troubleshooting notes:
Houseplants 70
Struggling to save a plant? The plant rescue guides walk through recovery step by step, and the problem solver works backwards from a symptom. This is general growing advice, not a diagnosis for a specific plant.