Mealybugs
Mealybugs are soft, oval, sap-sucking insects coated in white, waxy, cotton-like fluff.
Mealybugs at a glance
| Also known as | Woolly aphid relatives, cottony scale |
|---|---|
| Affected parts | Leaf axils, shoot tips, roots |
| Most at risk | Tropical/indoor trees (ficus, jade, succulents, fukien tea, serissa) |
| Main cause | Soft, waxy sap-sucking insects hiding in sheltered nooks |
| Severity | Moderate; persistent indoors, can infest roots |
| Reversible? | Yes with repeated, thorough treatment |
What to look for
- Leaves: White, cottony tufts in leaf axils, along veins, and at shoot tips; sticky honeydew and black sooty mold; yellowing and stunted, distorted growth.
- Roots: Root mealybugs appear as white, mealy, fluffy deposits on roots and the inside of the pot — found when repotting.
- Whole tree: Cottony specks that look like mold but pull apart to reveal insects; ants; slow decline indoors.
Overview
Mealybugs are soft, oval, sap-sucking insects coated in white, waxy, cotton-like fluff. They tuck into sheltered spots — leaf axils, shoot tips, the undersides of leaves, even on the roots — and are most troublesome on tropical and indoor bonsai. The waxy coat repels water and many sprays, so they take persistence to clear.
Causes
Warm, stable indoor conditions; introduction on new plants; overfeeding driving soft growth; and undisturbed sheltered nooks where colonies build.
Commonly confused with
Powdery mildew and woolly fungus look white too — but mealybugs are discrete cottony lumps that move/squash to a yellow smear, found in axils. Soft scale is fixed and shell-like; mealybugs are mobile and fluffy. Whitefly fly off when disturbed.
Which species are affected
Mostly tropical and indoor species: ficus, jade and other succulents, fukien tea, serissa, citrus-relatives, schefflera; occasionally outdoor trees.
Treatment
Dab each insect with a cotton bud of (diluted) isopropyl alcohol to break the waxy coat; then spray insecticidal soap, neem, or horticultural oil thoroughly into all nooks, repeating weekly for several weeks. For root mealybugs, bare-root, wash, and repot into fresh soil, treating with a soil drench. Isolate the tree; control ants.
Prevention
Quarantine and inspect new plants (and their roots at repotting); avoid over-feeding; check axils and tips regularly; keep good airflow.