What's eating my euphorbia polygona?

Euphorbia polygona (snowflake euphorbia) is a multi-ribbed houseplant succulent most commonly affected by mealybugs hiding in its numerous tight rib channels. Scale insects can colonise the stem surface, and spider mites cause stippling in low-humidity rooms. Root mealybugs are a risk in compacted or overly moist compost. Gloves essential when treating.

White fluffy clusters in rib channels and at the crown; the many ribs provide ideal shelter; plant yellows and growth stalls Work systematically along every rib with an alcohol-soaked cotton bud; spray neem oil; repeat fortnightly; wear gloves against latex sap

Flat or rounded bumps on rib edges and spine nodes; feeding weakens stem tissue and generates sticky honeydew residue Scrape off carefully with a toothpick or soft toothbrush; wipe with alcohol; apply horticultural oil spray to discourage re-infestation

Fine pale or silvery stippling across the green epidermis between ribs; silk webbing at spine bases in heavy infestations Raise humidity around the plant; apply insecticidal soap spray to all surfaces; avoid hot, dry windowsill positions in winter