What's eating my euphorbia cylindrifolia?

Euphorbia cylindrifolia is a small, caudex-forming succulent from Madagascar that is generally pest-resistant indoors. Mealybugs are the most likely problem, hiding at the base of the caudex and in the growing tips. Spider mites can flare in overly dry conditions. Root mealybugs occasionally attack below the soil.

White cottony deposits at the caudex neck and stem tips; honeydew; tips wilt or leaves drop prematurely Treat with isopropyl alcohol on cotton swabs; spray neem oil or insecticidal soap over the whole plant; repeat weekly

Unexplained wilting and failure to thrive despite correct watering; white powdery colonies on roots after unpotting Remove plant from pot; rinse roots; soak in neem or imidacloprid solution; repot in clean, dry compost

Very fine pale stippling on leaf or stem surfaces; dull appearance; barely visible webbing in dry air Increase ambient humidity slightly; wipe foliage; apply insecticidal soap or neem oil every 5-7 days