Winter Houseplant Pests: ID and Organic Control

By James Wilson · October 7, 2026

Why Pests Thrive Indoors in Winter

Warm, dry air, stressed plants, and no natural predators create perfect conditions for indoor pest outbreaks.

The Big Four

1. Spider Mites

Tiny arachnids thriving in dry air. Signs: fine webbing, stippled yellow dots, leaf bronzing. Treat: increase humidity above 50%, spray with neem oil (2 tsp neem + 1 tsp dish soap per quart) every 5 days.

2. Mealybugs

White cottony masses in leaf axils. Treat: dab with 70% isopropyl alcohol, spray with insecticidal soap weekly for 3–4 weeks.

3. Fungus Gnats

Small black flies at soil surface. Treat: let soil dry between waterings, use yellow sticky traps, apply Bti (Mosquito Bits) drench.

4. Scale Insects

Brown shell-like bumps on stems. Treat: scrape off individually, apply horticultural oil every 7–10 days for 3–4 applications.

Prevention

Quarantine new plants for 2 weeks
Inspect leaf undersides weekly with a 10x loupe
Wipe leaves monthly with a damp cloth
Avoid over-fertilizing — excess nitrogen attracts pests