Fungus Gnats in String of Pearls — A Watering Problem in Disguise
String of Pearls (Curio rowleyanus (formerly Senecio rowleyanus))
Symptoms
- small dark flies hovering around the hanging basket
- flies emerging from soil when disturbed
- larvae in the top inch of soil
Causes
Persistently moist soil from overwatering
Fungus gnats breed only in consistently moist organic soil, and this succulent's pearl-shaped leaves are built to go long stretches on stored water between waterings — so a gnat population showing up in a hanging basket is really a watering-habit tell, not a pest problem in its own right. Treat the flies and you've only masked the real issue underneath.
How to Fix It
- 1
Stop watering on whatever schedule led to this and go back to checking the basket's actual dryness before adding more — for a plant this well-adapted to drought, a gnat problem only ever means the routine has drifted from what the pearls actually need.
- 2
Apply Bti (Bacillus thuringiensis var. israelensis) as a soil drench. Mosquito Bits dissolved in water and applied to soil kills fungus gnat larvae specifically. Repeat weekly for 4–6 weeks.
- 3
Once the population is under control, top-dress with fine grit or coarse sand — it suits this succulent's own preference for a mineral surface anyway, and it dries out too fast for gnats to lay eggs in.
Prevention
- Let the basket go properly dry before the next watering, leaning on the pearls' own water reserve rather than a fixed schedule, so the soil surface never stays damp long enough for gnats to establish
- Sand top-dressing after repotting prevents establishment
Quick Summary
| Plant | String of Pearls (Curio rowleyanus (formerly Senecio rowleyanus)) |
|---|---|
| Category | Pests |
| Likely causes | Persistently moist soil from overwatering |
| Fix steps | 3 steps — see above |