What's eating my variegated moon cactus?

Variegated Moon Cactus (Gymnocalycium mihanovichii f. variegata) is a grafted houseplant with two plants in one — both the colorful scion and the green rootstock can be attacked. Mealybugs are the top threat, clustering at the graft union. Spider mites and scale also occur. Monitor the graft junction closely, as pests hide there and damage can be fatal.

White cottony wax at the graft union or in the ribs, wilting of the colored scion Apply isopropyl alcohol carefully at the union and ribs; neem oil spray on the rootstock; avoid wetting the union excessively

Stippling and faint webbing on the rootstock's ribs; the colorful scion may show discoloration Neem oil spray every 5–7 days; improve airflow and avoid very dry, hot conditions

Hard tan or brown bumps on the rootstock stem, particularly near the base or graft site Scrape off with a toothpick or soft brush, swab with alcohol, and apply horticultural oil to prevent recurrence