Plant care guide
ZZ Plant Mealybugs: Where They Hide and How to Clear Them
Updated · First published
Why does my Zz plant have mealybugs?
White, cottony tufts on a ZZ plant, under the leaflets, where leaflets join the stalk, or at the base of the stalks, are mealybugs. ZZ is rarely troubled by pests, so they usually arrive on another plant. Flat, brown, immobile bumps are scale instead.
What to do first
Isolate the ZZ, wipe each mealybug off with a cotton swab dipped in rubbing alcohol after testing a leaflet, and clear any mix around the stalk bases to reach hidden ones. Repeat until no new tufts appear, and check the rhizomes if the plant keeps declining.
A ZZ plant is supposed to be the one that never causes trouble, so white fluff on it is a surprise. It does happen. Iowa State Extension lists ZZ plants among the houseplants where mealybugs are commonly found, alongside succulents, Ficus and Dracaena.
UF/IFAS describes ZZ as resistant to diseases and pests (EP252). So when mealybugs turn up, look for where they came from: a new plant, or a neighbour whose leaves touch the ZZ.
Confirm it is mealybugs
Iowa State describes mealybugs as small oval insects covered in white, powdery wax, about 3–6 mm (1/8–1/4 in) long. Their egg masses look like puffs of cotton. They leave sticky honeydew that can turn black with sooty mould.
Rule out scale. NC State Extension says ZZ has no significant problems, but to watch for scale insects. Scale looks like flat or domed brown bumps that do not move and have no cottony wax.
Where they hide on a ZZ
Each ZZ leaf is a thick stalk carrying six to eight pairs of glossy leaflets, rising from a rhizome under the mix (NC State). Check:
- Leaflet undersides and the point where each leaflet joins the stalk. Washington State University Extension lists leaf undersides, joints and crevices as feeding sites (WSU: Mealybugs).
- The base of the stalks at the soil line. WSU says mealybugs feed at the base of the plant and even below the soil.
- The rhizomes and roots. UW–Madison Extension says small white cottony masses around drainage holes suggest root mealybugs (UW–Madison: Mealybugs).
What to do
- Isolate the plant. UW–Madison says mealybugs crawl from plant to plant, especially where leaves overlap.
- Test alcohol on one leaflet. UC IPM advises a solution of 70% or less isopropyl alcohol, tested 1 to 2 days ahead for leaf burn (UC IPM Pest Note 74174).
- Swab every mealybug and egg mass. Iowa State recommends an alcohol-soaked cotton swab for light infestations.
- Clear the stalk bases. WSU says removing soil around the crown may be needed to reach mealybugs below the surface.
- Treat again. Iowa State says houseplant sprays with insecticidal soap, pyrethrin or neem can be used. Check the label lists both mealybugs and your plant. Treat persistently, because new nymphs keep hatching.
- Inspect the rhizomes if the ZZ yellows or stalls. UW–Madison says root infestations are often confirmed only by removing the root ball, and are hard to control.
If the roots are infested
UW–Madison says replacing a plant is often the most practical way to deal with root mealybugs. UF/IFAS notes that ZZ can be propagated from leaf cuttings or by dividing the rhizomes. Take only clean leaflets, check them closely, and root them in fresh mix in a clean pot.
Pets and people
UF/IFAS says all parts of the ZZ plant are toxic if ingested. Iowa State Extension regards it as poisonous to humans and pets. NC State lists calcium oxalate as the toxic principle. Keep trimmings and treated swabs out of reach.
Prevent a return
- Quarantine new plants and check leaflet bases before they join the ZZ.
- Keep pots apart so leaves do not touch.
- Keep the ZZ on the dry side. Iowa State advises letting the mix dry nicely between thorough waterings.
Our mealybugs guide covers mealybug biology and treatment in depth. For spots on the leaflets, see ZZ plant brown spots, and for routine care, the ZZ plant care guide or the ZZ plant hub.
References
- Iowa State University Extension and Outreach: Mealybugs
- NC State Extension Gardener Plant Toolbox: Zamioculcas zamiifolia
- UF/IFAS Extension EP252: Cultural Guidelines for Commercial Production of Interiorscape ZZ
- UF/IFAS Gardening Solutions: ZZ Plant
- Washington State University Extension: Mealybugs
- UW–Madison Extension: Mealybugs
- UC Statewide IPM Program: Pest Notes: Mealybugs (Publication 74174)
- Iowa State University Extension and Outreach: Zamioculcas
How this guide was put together: Iowa State University Extension, NC State Extension, UF/IFAS Extension, Washington State University Extension, UW–Madison Extension and UC Statewide IPM Program guidance.