Pests

Mealybugs

White cottony clusters tucked into leaf joints and along stems, leaving sticky honeydew behind.

What you'd see

White, waxy, cotton-wool tufts in leaf axils, under leaves and where leaf meets stem
Sticky shine on leaves or the surface below the plant (honeydew)
Black sooty mould growing on the honeydew
Yellowing, weak growth and leaf drop on a plant that otherwise seems well watered

Where to look

Tight crevices: leaf joints, under the pot rim, in the roots of succulents (root mealybugs) and inside new growth.

How it spreads

Slow walkers but excellent hiders. Crawlers move to neighbouring pots that touch, and they arrive on new plants.

Is it really this? Look-alikes

Woolly aphids — Rare indoors; woolly aphids cluster on woody stems and move as a colony.
Perlite or fungal fluff — Fluff that does not smear pink or orange when squashed is not a mealybug.

What's going on

Mealybugs are soft-bodied scale relatives that suck sap and coat themselves in a protective wax. That wax is why water alone rolls off them.

They favour plants that are slightly stressed or over-fertilised with nitrogen, which makes for soft, sugary tissue.

Why?

The wax coat explains every remedy: alcohol dissolves it on contact, soap and oil smother through it, and systemic treatments bypass it by poisoning the sap. Knowing this stops you wasting time misting them with water.

Grandmother's remedies

What people have always done — with an honest note on each.

Cotton bud and rubbing alcohol
Dip a cotton bud in 70% isopropyl alcohol and touch each mealybug. They dissolve. Repeat weekly.
Verdict: The single most effective home method for a light to moderate case. Tedious, and that is the point.
Soap and water scrub
A soft toothbrush and mild soapy water on stems and leaf joints.
Verdict: Good for physical removal on tough-leaved plants; less so on soft foliage.
Repot and root wash
For root mealybugs on succulents: bare-root, rinse, inspect, and repot in fresh mix.
Verdict: Necessary rather than optional for root mealies — nothing else reaches them.

Modern remedies

What growers and extension services reach for today.

Insecticidal soap or horticultural oil
Spray to run-off into every crevice every 7 days, three rounds.
Verdict: Effective on crawlers, weak on wax-covered adults — combine with the alcohol method.
Ladybird larvae (Cryptolaemus)
The 'mealybug destroyer' released in warm conditions.
Verdict: Works well in conservatories and large collections; needs warmth above 20 °C.
Systemic insecticides
Applied to soil so the plant's sap becomes toxic.
Verdict: Effective but hard on pollinators and beneficial insects if the plant ever flowers outdoors; a last resort indoors.

Honest verdict

Mealybugs are persistent because eggs sit in wax sacs where spray cannot reach. Plan on a month of weekly checks. If a plant is smothered and you have others nearby, composting it is a valid choice, not a failure.

Prevention

Isolate new arrivals and inspect leaf joints with a torch
Avoid high-nitrogen feeding that produces soft growth
Keep pots from touching
Wipe pot rims and saucers when you repot

Plants this commonly troubles

Monstera Pothos Snake plant Fiddle-leaf fig Philodendron