Fruit flies usually breed in moist, fermenting plant material such as overripe fruit, trash residue, bottles, dirty drains, or spills under appliances. Finding the breeding source works better than killing individual adult flies.
Look for moist fermenting material
Check fruit bowls, stored potatoes or onions, compost containers, drink bottles, and trash bags. One forgotten piece of produce can support many generations even when the kitchen looks clean.
Do not assume the drain is the source
Fruit flies may feed around drain residue, but other small flies specifically breed in pipe biofilm. Cover the drain overnight or inspect the adults closely before deciding the drain is the source.
Remove the source and sticky residue
Discard spoiled produce, wash containers, and clean spills beneath bins or appliances. Temporarily refrigerate ripe fruit to remove additional egg-laying sites while the infestation declines.
Traps catch adults but do not replace sanitation
A baited trap can reduce adults and help track the trend, but continued emergence means a moist breeding source remains. Keep searching until the population declines for several days.
Sources
- U.S. Environmental Protection Agency — Integrated Pest Management — Integrated pest management using sanitation, exclusion, monitoring, and targeted treatment.