What's eating my peanut cactus?

Peanut Cactus (Echinopsis chamaecereus) is a clustering, low-growing houseplant whose many finger-like branches provide excellent hiding spots for mealybugs. Scale insects are also common. Root mealybugs can infest unnoticed between the crowded offsets. Spider mites occasionally appear during hot, dry spells.

White fluffy wax in the crevices between the clustered stems; segments yellow, shrivel, and drop Dab all infested joints with 70% isopropyl alcohol; spray with dilute neem oil; separate heavily infested offsets

Unexplained wilting and shrivelling of otherwise healthy-looking segments; white waxy colonies on roots Unpot, inspect roots, apply a neem soil drench or systemic treatment, and repot in fresh dry cactus compost

Small brownish bumps on stem surfaces; segments lose colour and firmness around the affected area Scrape off with a toothbrush; treat with horticultural oil or insecticidal soap spray every 2 weeks