Mealybugs
TreatablePest · spreads to other plants
Mealybugs are the classic houseplant pest, and they hide in exactly the places that are hardest to spray — leaf joints, under the rim of a pot, and in the roots. The white fluff repels water and most sprays, which is why alcohol on a cotton bud remains the most effective home treatment.
What it looks like
Small oval insects covered in white cottony wax, hiding in leaf axils, under leaves and in the crevices where stems meet. Heavy infestations look like scattered specks of cotton wool. Sticky honeydew follows.
How to confirm it
- White cottony specks in leaf axils and crevices.
- The fluff repels water; a plain water spray runs straight off.
- Sticky residue on leaves below.
- Check the roots too — root mealybugs look like white powder in the soil ball.
What to do
- 1Dab each insect with a cotton bud dipped in rubbing alcohol. It dissolves the wax and kills on contact.
- 2For heavier infestations, spray with insecticidal soap or neem weekly for a month.
- 3Isolate the plant. Mealybugs walk to neighbours.
- 4If the plant declines despite clean foliage, unpot it and check the roots.
What it gets confused with
One observation settles each of these.
Scale is hard and flat and does not move. Mealybugs are fluffy and can walk.
Mildew is a flat dusty film across leaf surfaces; mealybugs are discrete lumps of fluff in crevices.
Preventing it next time
- Quarantine new plants for several weeks.
- Inspect leaf axils when watering.
Plants affected
Check these two things first
- Push a finger into the soil, two knuckles deep. Wet soil plus a wilting plant means too much water, not too little — and it is the commonest reason a plant is dying. Dry soil plus crisp leaves means the opposite. The leaves look nearly identical either way, so the soil is what tells you.
- Turn a damaged leaf over. Half of all diagnoses live on the underside: fuzz means downy mildew, fine webbing means spider mites, clusters of insects mean aphids. Nothing on the top of a leaf is as informative.
Most garden problems are cosmetic and resolve without treatment. Reach for a spray last, not first.