Houseplant flies in UK homes are usually fungus gnats (Bradysia spp.), which lay 200+ eggs in moist compost and complete their lifecycle in 3-4 weeks at 21C. Infestations peak in autumn and winter when central heating warms rooms to 18-22C. Yellow sticky traps catch 70-80% of adults within 48 hours. Steinernema feltiae nematodes kill 85-95% of larvae when applied above 10C.
Key takeaways
- Fungus gnats are the most common houseplant fly in UK homes, laying 200+ eggs in moist compost
- Their lifecycle completes in 3-4 weeks at 21C, so infestations multiply fast in heated rooms
- Yellow sticky traps catch 70-80% of adult gnats within 48 hours of placement
- Steinernema feltiae nematodes kill 85-95% of larvae and cost 8-12 pounds from UK suppliers
- Letting the top 3cm of compost dry between waterings prevents most infestations entirely
- Autumn and winter are peak seasons as plants come indoors into warm, centrally heated rooms
houseplant flies fungus gnats indoor pests houseplant care biological controls nematodes
Our team produces practical UK gardening guidance from source research, contributor records and established horticultural practice. Editorial standards are overseen by Matt W.
