What's eating my rat tail cactus?

Rat Tail Cactus is most vulnerable to mealybugs, which colonise the narrow ribbed stems and areoles, especially where stems overlap. Spider mites thrive in warm, dry indoor air. Hanging basket cultivation increases airflow but does not eliminate risk — check every stem joint and areole during watering.

White waxy wool in areoles and between overlapping stems; honeydew leading to sooty mould; yellowing stem segments Apply 70% isopropyl alcohol with a cotton swab to all woolly clusters; treat the whole plant with diluted neem oil solution every two weeks

Fine webbing along the length of pencil-thin stems; pale stippling or a dull, greyish cast to normally bright green skin Move plant outdoors and rinse stems thoroughly; apply miticide or insecticidal soap spray; repeat twice at seven-day intervals

Unexplained wilting and failure to grow despite correct watering; white powder visible on roots when repotted Unpot, shake off soil, and rinse roots; drench new well-draining mix with diluted neem or imidacloprid solution before repotting