Ivy Scale Infestation: Horticultural Oil Smothers Armored Pests

Dying Ivy

A large English ivy moved indoors for winter develops coated stems and dying leaves. Photo shows black bumps on stems.

Diagnosis: Scale Insects

The bumps are adult scale covers; living insects feed underneath, sucking sap. Conventional sprays fail—the waxy shield blocks chemicals.

Effective Treatment

1. Take plant outdoors (warm day) or to a ventilated garage.
2. Spray horticultural oil (SunSpray or similar) to dripping, covering all stems and leaf undersides.
3. Repeat weekly for 3–4 weeks.
4. Scales are dead when a strong water stream washes off the bumps.

Oil smothers—no resistance issues. Indoor infestations are common; inspect all houseplants.