Scale insects on fishbone cactus
How do I get rid of scale?
On fishbone cactus: Hard brown bumps on stems and midribs that do not move. Scrape them off first, because sprays bounce off the armour, then horticultural oil weekly for six weeks.
Hard brown or tan bumps, two to four millimetres across, on stems and along the midrib underneath leaves. They look like part of the plant and do not move. Scrape one with a fingernail: if it lifts off and leaves a damp mark, it is scale rather than bark.
Why this plant gets them
it is a large woody plant with plenty of stem, and scale prefers stems and midribs to soft new growth.
Drawn from this species' own record — humidity floor 45%, watering every 7–14 days, trailing habit. Full care entry.
The life cycle, and why one treatment fails
The armoured adult is immobile and effectively sealed under its own shell, which is why sprays largely bounce off it. Only the crawler stage, which is mobile and unarmoured, is genuinely vulnerable.
What actually clears them
Scrape the adults off physically with a fingernail or an old toothbrush — this is the step people skip and it is the one that matters. Then treat weekly with insecticidal soap or horticultural oil for six weeks to kill successive crawler generations. Oil works better here than soap because it smothers.
Spraying without scraping. The adults are armoured, they will survive, and they are still laying underneath. Systemic granules can work but are a poor idea on a plant a pet chews.
Other pests recorded for this species
- Mealybugs this week
Is it a pest at all?
Plenty of what looks like pest damage is a care problem. If you cannot actually find the insect described above, check the diagnosis pages for this species instead — root rot, no flowers, leggy growth — where the causes are ranked for this plant specifically.
Scale insects on other species here
42 other species in this database have scale insects recorded against them. The treatment is the same; only the reason they are prone differs.
- Pothos Araceae
- Fiddle leaf fig Moraceae
- Parlor palm Arecaceae
- Cast iron plant Asparagaceae
- Rubber plant Moraceae
- Boston fern Polypodiaceae
- Jade plant Crassulaceae
- Aloe vera Asphodelaceae
Sources
- North Carolina Extension Gardener Plant Toolbox — Selenicereus anthonyanus Extension pest guidance.
- Royal Botanic Gardens Kew, Plants of the World Online — Selenicereus anthonyanus Accepted name and family. Checked 2026-09-12.
- This database's own care record for Selenicereus anthonyanus — the humidity, watering and habit fields this page reasons from.
Compiled and edited by Tony Valcarcel · 2026-09-12
Treatment guidance is the standard approach for this pest and is not specific to
your plant's condition. If a plant is already collapsing, the pest may not be the
whole story. How this is sourced.