What's eating my red orchid cactus?

Red orchid cactus (Disocactus ackermannii) is susceptible to mealybugs and spider mites indoors, and to slugs if placed outside in summer. Its broad, flat stems create ideal hiding spots for scale too. Mealybugs are the most frequent problem, congregating at stem bases and joints where they are easy to miss.

White woolly masses at stem bases and along edges; sticky residue and wilting growth tips Apply 70% isopropyl alcohol with a cotton swab directly to colonies; follow with neem oil spray every 7–10 days

Pale speckling and fine webbing on stem surfaces; worst in heated, dry indoor air during winter Mist stems and increase room humidity; apply insecticidal soap, thoroughly wetting all stem surfaces

Shell-like brown bumps fused to stems; reduced vigour and yellowing over several weeks Scrape off with a soft brush dipped in alcohol; drench with horticultural oil or neem oil

Ragged holes and slime trails on flat stems when plant is placed outdoors in warm months Hand-pick at night; apply iron phosphate pellets; move pot to an elevated surface away from soil level