
Scale insects
Hard or soft brown bumps stuck to the woody trunk, leaf-petiole joints, and along the underside of leaves near the central vein, 1 to 4 mm wide. Look like tiny barnacles glued in place. Ficus species are famously scale-prone, more so than almost any other houseplant.
Yellowed patches around each cluster. A sticky shiny film on lower leaves and the floor below the plant, often with sooty black mold. Untreated colonies along the trunk can defoliate whole sections, dropping leaves up the woody stem until only the top tuft remains.
Scrape with a fingernail or soft toothbrush
Scale insects are stuck under a waxy seal. Scrape every visible bump off the trunk, petioles, and leaf undersides. Rubber plant's thick waxy leaves and woody trunk take a fingernail or soft toothbrush very well. Wipe up any white latex sap that seeps from scrape sites with a damp cloth.
Cotton swab + 70% alcohol, weekly for 4 weeks
After scraping, dab any remaining bumps with a cotton swab dipped in 70% isopropyl alcohol. The alcohol penetrates the waxy seal and kills the insect. Repeat weekly for 4 weeks because Ficus scale crawlers hatch in waves and the trunk hides them well.
Horticultural oil spray, every 7 days for 4 weeks
Spray horticultural oil (Bonide All Seasons, ~$15) over every leaf surface, the petiole joints, and the full trunk. Smothers crawlers and adults under their seal. The waxy leaf cuticle on rubber plant tolerates oil well. Apply at lights-out, every 7 days for 4 weeks.


