What's eating my desert rose?

Desert rose (Adenium obesum) is most commonly plagued by mealybugs tucking into the caudex folds and stem joints. Spider mites appear in hot dry indoor conditions. Scale insects colonise woody stems. Outdoors in warm climates, oleander aphids (bright yellow) attack new growth. Inspect the swollen base carefully at repotting.

White waxy fluff in stem crevices, trunk folds, and at leaf bases; plant grows slowly; leaves yellow and drop. Blast crevices with a water jet or cotton swab dipped in isopropyl alcohol; apply neem oil drench to the caudex; repeat every 10 days.

Pale speckling and dusty look on leaves; fine webbing in leaf axils in hot dry periods indoors or under glass. Increase humidity slightly (without overwatering the soil); spray neem oil or insecticidal soap on all leaf surfaces; repeat weekly.

Hard brown or yellow oval bumps on stems and caudex; sticky honeydew; sooty mould may follow. Scrub off with a toothbrush and soapy water; apply horticultural oil twice, 2 weeks apart.

Dense colonies of bright yellow-orange aphids on shoot tips and flower buds outdoors; curled new growth; honeydew. Knock off with water; apply insecticidal soap or neem oil; outdoors, parasitic wasps usually bring populations under control naturally.