What's eating my pelargonium echinatum?

Pelargonium echinatum, the cactus geranium, is a spiny-stemmed succulent houseplant. As an indoor plant it is most troubled by mealybugs sheltering among its thorns, and by spider mites in warm, dry rooms. Root mealybugs are a risk if overwatered compost is used, and fungus gnats breed in moist substrate.

White waxy cottony tufts collect in stem joints and around thorns; affected growth is weakened, sticky, and may develop sooty mould. Dab individual colonies with a cotton bud dipped in 70% isopropyl alcohol. Follow with an insecticidal soap spray; repeat every 7–10 days.

Fine stippling on leaves, pale bronzing of foliage, and fine webbing between stems — worst in hot, dry indoor air. Raise humidity around the plant; spray with neem oil or insecticidal soap. Repeat every 5–7 days for three to four weeks.

Adults are harmless nuisances; larvae feed on roots and organic matter in compost, stunting growth if populations are high. Allow compost to dry out between waterings. Apply Steinernema feltiae nematodes or Bacillus thuringiensis israelensis (Bti) to the soil; use yellow sticky traps for adults.