What's eating my thanksgiving cactus?

Thanksgiving Cactus (Schlumbergera truncata) is an indoor epiphytic cactus most commonly attacked by mealybugs hiding at stem segment joints. Fungus gnats breed in overwatered soil. Spider mites and scale also occur. Unlike desert cacti, its soft fleshy stems are especially vulnerable — check every joint when watering.

White waxy fluff at segment joints and in leaf axils; segments yellow and drop prematurely Swab all joints with isopropyl alcohol on a cotton bud; repeat every 7 days; isolate immediately

Adult gnats flying around the pot; larvae in waterlogged soil damage feeder roots causing wilting Allow topsoil to dry before re-watering; use sticky yellow traps; apply Bti-based soil drench

Fine webbing between segments; pale stippling on the flat stem surfaces, worst in dry heated rooms Wipe stems with a damp cloth; apply insecticidal soap or neem oil; raise local humidity

Brown shell-like bumps on stems and at segment joints; sticky deposits and yellowing Scrape off manually with a soft brush; treat with neem oil spray fortnightly until clear