Spider Mites on Outdoor Cacti: Identification and Natural Control

Confirming Spider Mites

• Fine webbing on stems/areoles.
• Stippling (tiny pale dots) on epidermis.
• Microscopic moving dots on white paper after tapping stem.
• Worsens in hot, dry, dusty conditions.

Natural Control Methods

1. High-pressure water spray weekly (undersides too) to dislodge mites.
2. Predatory mites (Phytoseiulus persimilis) released per supplier instructions.
3. Neem oil or insecticidal soap every 5–7 days for 3 weeks (test on small area first).
4. Increase humidity temporarily (misting) — mites hate moisture.

Chemical Last Resort

Miticides (e.g., abamectin, spiromesifen) only if natural methods fail. Rotate modes of action to prevent resistance. Always follow label for ornamental cacti.

Resource: Colorado State University extension guide (linked in original) for detailed IPM.