Spider Mites on string of pearls
What's Happening
Two-spotted spider mites (Tetranychus urticae) exploit the String of Pearls' (Senecio rowleyanus) preference for low-humidity conditions below 40% RH. The mite colony establishes itself in the pearl crevices where the waxy leaf coating provides protection and the trailing growth habit creates sheltered microhabitats. Dry indoor air typical of windowsill placement accelerates mite reproduction cycles.
How to Fix It
- 1
Confirm identification: Place humidifier near plant for 24-48 hours to force mites to become active and visible; inspect with phone flashlight for moving red/orange specks
- 2
Physical removal: Give plant a thorough warm shower, directing water spray into pearl crevices to dislodge mites and webbing
- 3
Contact treatment: Apply 70% isopropyl alcohol diluted 1:1 with water using cotton swabs on affected areas; avoid water-based sprays that promote rot
- 4
Systemic follow-up: Treat with neem oil or insecticidal soap weekly for 3 weeks, focusing on soil level and stem joints where eggs hide
- 5
Monitor: Use yellow sticky traps to catch dispersing adults; quarantine plant for 4 weeks minimum
How to Prevent It
Maintain ambient humidity between 40-50% using pebble trays or humidifiers rather than direct misting. Inspect new plants with a 10x loupe before introducing to collections. Space plants 1-2 feet apart to prevent silk-thread dispersal between specimens.