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Scale Insects

Small, immobile insects that attach to stems and leaves, feeding on sap under a protective waxy shell. They produce sticky honeydew and weaken plants over time.

Symptoms

  • check_circleBrown, tan, or white bumps on stems and leaf undersides
  • check_circleSticky honeydew coating leaves and surrounding surfaces
  • check_circleBlack sooty mould growing on honeydew
  • check_circleYellowing leaves and general decline
  • check_circleBumps that do not move when touched

Causes

  • arrow_rightIntroduction via infected plant material or tools
  • arrow_rightWarm, dry indoor conditions favour scale populations
  • arrow_rightStressed or weakened plants more vulnerable
  • arrow_rightAbsence of natural predators indoors

How to Diagnose

Run your finger along stems — scale insects feel like hard or waxy bumps and do not brush off easily. Scrape one off to confirm: it will have a soft body underneath the shell.

Treatment

For light infestations, scrape off scale manually with a soft toothbrush or cotton swab dipped in rubbing alcohol. For larger infestations, apply neem oil or an insecticidal soap spray, ensuring coverage of stems and leaf undersides. Repeat every 7–10 days for 4–6 weeks.

Prevention

Inspect new plants thoroughly before bringing them home. Maintain good plant health to resist infestation. Avoid over-fertilising with nitrogen, which produces soft growth that scale prefer.

Scale Insects in Plants | GreenScout