Scale insects are oval, raised bumps that scrape off. “Tiny black lines” don’t match any common palm pest. A clear photo would help. Mealybugs (white cottony) were correctly treated.
Monitor. If lines spread or change, photograph and consult.
Date Palm Leaf Spots: Environmental Stress, Not Infectious Disease
White Scale on Sago Palm: Persistent Asian Cycad Scale
Sago Palm Frond Browning: Cold Injury or Overwatering
Cold Damage in Nepenthes jamban: Garage Temperature Risks
30-Year Madagascar Palm Decline: Light Reduction and Overpotting
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