Spider mites
Almost invisible without a hand lens. Yellow-green to red-orange specks running along the underside of leaflets, especially where the leaflets meet the central petiole. Indoor heated air through winter dries money tree leaves and triggers a population boom.
Tiny pale yellow dots tiny pale dots the leaflet underside, then bronze patches that spread across the upper surface. Fine webbing strung between leaflets. Affected leaflets curl, yellow, and drop weeks earlier than normal, leaving thin sparse foliage.
Shower the leaves weekly for 3 weeks
Move the money tree to the shower or sink. Spray cool water on the underside of every leaflet for 30 seconds, then the upper surface. Money tree's smooth leaflets handle a hard rinse well. Mites can't reattach quickly when knocked off, and the rinse humidity slows survivors. Repeat weekly for 3 weeks.
Neem oil at lights-out, every 5 days for 3 rounds
Mix 2 tablespoons cold-pressed neem oil and 1 teaspoon dish soap per gallon of water.
Spray every leaflet, top and bottom, at lights-out, paying attention to the petiole junction where mites cluster.
Repeat every 5 days for 3 rounds. That covers the full egg-to-adult life cycle.
Raise winter humidity above 50%
Run a humidifier near the money tree for 50 to 60% relative humidity through winter. Money tree evolved in tropical wetlands and tolerates higher humidity well. Hot dry indoor heating is exactly the climate spider mites need to breed fast.
