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.

Fix it

What the treatment above uses, from our shop:

Neem Oil Organic Concentrate 2 Ounces $14.95

Prevention

Quarantine and inspect new plants (and their roots at repotting); avoid over-feeding; check axils and tips regularly; keep good airflow.