What's eating my gymnocalycium andreae?

Gymnocalycium andreae is a small, smooth-bodied cactus susceptible to mealybugs sheltering in its areoles and root mealybugs in the soil. Spider mites can settle on the skin in dry conditions. Scale insects are an occasional threat. Its compact size means infestations spread fast if the plant is not quarantined promptly.

Cottony white deposits at the base of spines and in stem grooves; reduced vigour and dull colouration Remove with alcohol-dipped cotton bud; spray with neem oil or insecticidal soap; repeat weekly and isolate the plant

Persistent wilting and growth failure; white, waxy fluff found on roots and inner pot wall Unpot, rinse roots clean, soak briefly in imidacloprid solution, air-dry fully, repot in fresh gritty-free-draining mix

Faint russeting or stippling on the smooth green surface; very fine webbing at areoles in severe cases Wipe surface with damp cloth; apply insecticidal soap spray every 5 days for three rounds; avoid very low humidity