Scale insects

Small, hard, brown, immovable bumps along the leaves and trunk — often with sticky residue nearby — are scale insects.

Diagnosis

Scale insects

What's happening

Scale are sap-sucking insects that hide under a hard, waxy shell, so they look like raised brown or tan bumps stuck fast to the leaves and trunk. They drain the plant's sap, which weakens it and causes yellowing, and they excrete sticky honeydew that coats nearby surfaces and can grow sooty black mold. Because the shell protects them, they're stubborn to clear.

How to fix it

Isolate the plant. Scrape or rub off the visible scales with a cotton swab dipped in rubbing alcohol, or pick them off by hand, then wipe down the leaves to remove the sticky honeydew. Follow up by spraying the whole plant with insecticidal soap, getting into the crown and leaf bases where scale hides, and repeat every 7–10 days for several weeks. Inspect new growth closely, since crawlers can reinfest from any you missed.

What fixes it

  • Insecticidal soap — Insecticidal soap clears the soft crawler stage of scale; repeat after wiping off the adult shells.

If that doesn't fix it

This is general guidance based on common symptoms; individual plants vary.

Reviewed June 2026 · how we check this