Mealybugs

How to know it's mealybugs

White cottony masses tucked into leaf axils, along stems, under the rim of the pot and down in the root crown. Sticky honeydew, often with sooty mould. Mealybugs coat themselves in wax, which is exactly why contact sprays disappoint — the wax sheds the spray and the insect underneath carries on.

What eats them

Montrouzieri (Cryptolaemus montrouzieri) is the mealybug destroyer, and the name is earned. Both the adult beetle and its larva feed on mealybugs at every stage, including the egg sacs. The larva is the odd one — it grows its own white waxy coat and looks almost exactly like an oversized mealybug, which is how it walks into a colony unchallenged. If you see a big fuzzy white thing moving, that's the good guy.

Amblyseius swirskii takes mealybug crawlers, the mobile first stage. It won't touch an established adult, but it intercepts the dispersal stage, which is how an infestation spreads from one plant to the next.

Rhyzobius lophanthae is worth adding if what you actually have is scale — the two get confused constantly, and they need different beetles.

What to expect

Montrouzieri is a hunter, not a sprayer, so give it time to find the colonies. Warmth helps; it's a tropical species and slows right down in a cold room. Check the root crown and the underside of the pot rim before you decide the release didn't work — that's usually where the remaining population is sitting.