What's eating my fire crown cactus?

Fire Crown Cactus (Rebutia fiebrigii) faces the same indoor pest pressures as other small clustering cacti: mealybugs are the primary threat, hiding at stem joints and the soil line. Scale insects and root mealybugs also appear. Good air circulation and dry soil between waterings greatly reduce risk.

White waxy fluff at the base and in the areoles; plant may shrivel or fail to flower Remove with alcohol-dipped swabs; repeat weekly; use a systemic insecticide (imidacloprid granules) for persistent infestations

Brown or tan shell-like bumps on the stem; sticky honeydew residue; sooty mold may follow Scrape off manually, treat with neem oil or horticultural oil; repeat every two weeks

Wilting unrelated to watering; white powdery coating on roots found at repotting Remove from pot, wash and inspect roots, treat with diluted neem drench, repot into sterile dry mix