What's eating my silver ball notocactus?

Silver Ball Notocactus (Notocactus scopa) is a small woolly-spined globe cactus where mealybugs are the primary houseplant pest, hiding in its dense white wool and fine spines. Scale insects and root mealybugs are common secondary problems. The white wool camouflages mealybug colonies — inspect at every watering using a magnifying glass.

Cottony pest masses are nearly invisible against the plant's natural white wool; feeding causes paling and softening of the globe. Part the wool and treat with 70% isopropyl alcohol on a fine swab. Spray neem oil across the whole plant; repeat every 7–10 days.

Hard brown or tan discs on the rib surface beneath the wool; localized yellowing and stunted growth. Remove scales with a toothpick and alcohol swab. Apply neem oil spray, ensuring thorough penetration under the wool canopy.

Unexplained wilting and failure to grow despite proper care; white waxy fuzz on roots discovered at repotting. Unpot, wash roots clean, let dry, and repot in fresh sterile cactus mix. Drench soil once with a dilute systemic insecticide.