What's eating my turk's cap cactus?

Turk's Cap Cactus (Melocactus matanzanus) is a challenging houseplant crowned with a distinctive woolly cephalium. Mealybugs target the cephalium and rib grooves. Root mealybugs are a serious threat because this plant resents repotting, delaying treatment. Scale insects and spider mites are secondary concerns. Never disturb the cephalium — it will not regrow if damaged.

White fluffy deposits in the cephalium wool and between ribs; feeding weakens the plant and can cause cephalium collapse if severe Very carefully dab the cephalium and ribs with isopropyl alcohol on a fine brush; apply neem oil spray to the body only (avoid saturating the cephalium); repeat every 10 days

White powdery residue on roots; plant stops producing cephalium growth or new spines; basal rot may follow Treat with a soil drench of imidacloprid solution to avoid repotting stress; only repot as a last resort using a very well-draining mix

Hard, flat shields on rib skin; yellow patches around feeding sites on an otherwise healthy-looking body Gently scrape off with a soft toothbrush; apply diluted neem oil to the body; repeat after 10–14 days