What's eating my pelargonium triste?

Pelargonium triste is a geophytic houseplant with a tuberous base and finely divided foliage. Indoors it is most vulnerable to mealybugs lodging in leaf axils and root mealybugs attacking the tuber. Spider mites can cause stippling in dry conditions; fungus gnats are attracted to moist compost during its growing season.

White waxy fluff in leaf axils and near the tuber neck; foliage loses vigour and becomes sticky with honeydew. Apply isopropyl alcohol with a cotton bud to visible colonies. Spray the whole plant with insecticidal soap every 7–10 days until clear.

White powdery insects on roots and around the tuber; plant wilts despite adequate watering and growth slows dramatically. Unpot and rinse roots; soak the tuber in a dilute insecticidal soap solution. Repot into fresh, sterile grit-based compost.

Tiny pale stippling on the finely cut foliage; fine webbing appears in severe infestations, especially in hot, dry rooms. Increase humidity; spray with neem oil or insecticidal soap. Avoid overhead watering which can damage the delicate foliage.