What's eating my carrion flower (stapelia gigantea)?

Carrion Flower is a South African succulent grown for its large, odorous blooms. Indoors and outdoors it is mainly threatened by mealybugs and root mealybugs, which exploit the soft stems. Flies are deliberately attracted by the carrion scent for pollination — they are not pests. Overwatering causes rot that mimics and compounds pest damage.

White waxy colonies at stem joints and bases; soft stems may collapse or discolour at feeding points. Apply 70% isopropyl alcohol with cotton swabs to all colonies. Use a dilute neem drench if infestation spreads to the root zone.

Stems shrivel despite adequate watering; white deposits on roots and inside the pot. Unpot entirely, wash roots, soak in neem solution or dilute systemic insecticide, repot in fresh, very porous cactus mix.

Flat tan or brown discs along the angles of the four-cornered stems; sticky honeydew attracts sooty mould. Scrape off manually then wipe with alcohol. Treat the whole plant and inspect surrounding plants.