Pest identification
What's eating my euphorbia grandicornis?
Mealybugs
Signs: White waxy clusters in the rib grooves and around the spines; honeydew; slow growth or yellowing
Control: Dab with isopropyl alcohol swabs (wear gloves); follow up with neem oil spray; repeat weekly for 3–4 weeks; isolate the plant
Spider mites
Signs: Stippled or dull patches on the green stem; fine webbing in spine grooves in dry indoor conditions
Control: Apply insecticidal soap spray; boost humidity slightly; maintain good air circulation; treat every 5–7 days
Scale insects
Signs: Hard dome-shaped brown scales stuck to ribs and spine bases; pitting or discolouration of stem tissue
Control: Scrape off with a soft brush (gloves required); treat with horticultural oil; repeat after 10–14 days
Keep euphorbia grandicornis pest-free
Healthy plants resist pests best. Get the basics right:
Euphorbia grandicornis pests — FAQ
What is eating my euphorbia grandicornis?
Euphorbia grandicornis (cow horn euphorbia) is susceptible to mealybugs and spider mites, which settle along its deeply winged, ribbed stems and sharp horn-like spines. Scale insects can also attach to the stem ridges. Wear thick gloves when treating — the milky latex sap causes severe skin and eye irritation. Root rot is the main non-pest threat.
How do I get rid of mealybugs on euphorbia grandicornis?
White waxy clusters in the rib grooves and around the spines; honeydew; slow growth or yellowing Dab with isopropyl alcohol swabs (wear gloves); follow up with neem oil spray; repeat weekly for 3–4 weeks; isolate the plant
How do I get rid of spider mites on euphorbia grandicornis?
Stippled or dull patches on the green stem; fine webbing in spine grooves in dry indoor conditions Apply insecticidal soap spray; boost humidity slightly; maintain good air circulation; treat every 5–7 days
How do I get rid of scale insects on euphorbia grandicornis?
Hard dome-shaped brown scales stuck to ribs and spine bases; pitting or discolouration of stem tissue Scrape off with a soft brush (gloves required); treat with horticultural oil; repeat after 10–14 days