Identify the type: drain flies (near sinks/drains), fungus gnats (near plants/soil), fruit flies (near produce/trash)
Eliminate standing water and wet organic matter
Clean and scrub all sink and tub drains
Remove and clean drain stoppers and strainers
Pour boiling water down drains (safe for your plumbing) and repeat daily for several days
Use a drain brush to remove buildup in the drain
For drains: use a commercial enzyme or bacteria drain cleaner as directed
Fix leaks under sinks, around toilets, and in pipes
Empty and clean trash cans regularly; rinse and dry bins
Store fruit and produce in sealed containers
Wipe up spills and sticky residue promptly
Clean recycling bins and under-sink areas
Vacuum adult gnats and nearby surfaces
Use sticky traps near affected areas to reduce adults
For fungus gnats: allow the top 1–2 inches of potting soil to dry out between waterings
Water plants from the bottom to keep the soil surface drier
Remove dead leaves and decaying plant matter on top of soil
Replace heavily infested potting soil if needed
Use a layer of sand or fine gravel on top of potting mix to block egg-laying
Apply an appropriate treatment for fungus gnats (e.g., Bacillus thuringiensis israelensis, following label directions)
Consider beneficial nematodes for soil-dwelling larvae (following label directions)
Seal cracks and gaps around windows/doors
Keep screens intact and closed
Run dehumidifiers or improve ventilation to reduce dampness
After treatment, keep monitoring for 1–2 weeks to ensure the life cycle is broken