What's eating my copiapoa hypogaea?

Copiapoa hypogaea, a near-stemless species with a large underground caudex, is especially vulnerable to root mealybugs that attack both its fleshy root system and base. Spider mites and surface mealybugs are secondary threats. Inspecting the caudex and roots at repotting is the best early-warning strategy.

Wrinkled or deflated body despite adequate water; white wool on the caudex and roots Unpot, clean all root material, treat with systemic insecticide drench; repot in very gritty, sterile mix

White cottony clusters around the base, spine axils, or where body meets soil Dab with alcohol on a cotton swab; follow up with dilute neem oil drench

Fine webbing and stippling on the cactus body surface in dry, warm conditions Isolate plant; apply miticide or neem oil; ensure good ventilation around the plant