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How to identify it
- Adults are about 1/8 inch (2 to 4 mm) long, with a stout body and usually red eyes. Kentucky describes the front of the body as tan and the rear as black.[1][2][3]
- Some kinds have black eyes. Texas A&M says these dark-eyed fruit flies breed more often in drains and around bathrooms.[3][2]
- They hover and fly quickly and erratically, often around fruit bowls and trash cans.[2]
- Under a hand lens, a feathery bristle on the tip of each antenna sets them apart from other small indoor flies.[3]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Drain (moth) fly | Fuzzy and moth-like, with broad hairy wings held roof-like over the body; rests on walls near drains and makes short hopping flights when disturbed.[4][2][3] |
| Fungus gnat | Slender, dark and mosquito-like with long legs and antennae; a weak flier that stays near potted plant soil.[2][5] |
| Phorid fly | About the same size, but humpbacked, without red eyes, and inclined to run quickly across surfaces instead of flying when disturbed.[2][6] |
Where it lives
Common wherever food is allowed to rot or ferment: kitchens, restaurants and supermarkets. Besides produce, they breed in drains, garbage disposals, empty bottles and cans, trash and recycling bins, mops and rags.[1]
Biology and life cycle
A female can lay about 500 eggs near the surface of fermenting food or other moist organic material.[1][2]
The life cycle from egg to adult takes about a week: Kentucky gives 8 to 10 days at around 77°F, and Texas A&M says as few as 8 days under the best conditions. Adults live about a month.[1][2][3]
Larvae feed near the surface of the fermenting material, on the yeasts that grow in it, so damaged or overripe parts of produce can be cut away without throwing out the rest.[1][3]
Infestations start from produce that already carries eggs or larvae, or from adults that fly in through open doors and windows.[1][2][3]
Damage and signs
- A single forgotten rotting potato or onion, or juice spilled under the refrigerator, can produce thousands of fruit flies.[1]
- Outside the fruit bowl they breed in spilled syrup, wine or beer under kitchen equipment and bars, in cracks under damaged floor tile, and in the wet bottoms of trash cans where liners have leaked.[3]
- Because they can contaminate food, an infestation can force food businesses and healthcare facilities to close for cleaning.[2]
Health risk
Fruit flies can carry bacteria to food. In a USDA laboratory study, fruit flies collected from a compost pile of decaying fruit picked up a harmless marker strain of E. coli inside and outside their bodies after contact with it and carried it to clean apple wounds, where it multiplied; the authors said tests under commercial conditions were still needed. A survey in Nigeria found bacteria on house flies and fruit flies caught at markets, homes and other sites, with fruit flies carrying the smallest loads.[7][8]
Control
Keep them out
Use tight-fitting 16-mesh screens on windows and doors, and seal home-canned goods, wine, cider and beer containers so flies can't lay eggs under the lids.[1]
Sanitation
Find and remove every breeding source: eat, refrigerate or discard ripe produce, clean spills, and empty and wash trash and recycling bins. Without this, the problem continues no matter how many adults you kill.[1][2][3]
Check the less obvious spots too: under trash can liners, under and around the feet of the refrigerator, and loose lids on vinegar, wine or cider. Hang mops so they dry.[3][1]
Traps and physical control
To check a drain or disposal, tape a clear plastic bag over it overnight and look for trapped flies. Texas A&M suggests a strip of clear packing tape across the drain instead, leaving part of the opening uncovered so air still moves.[1][3]
Trap remaining adults with a jar of cider vinegar topped with a paper funnel, or vinegar with a drop of dish soap.[1][2]
Pesticides
A pyrethrum aerosol can kill remaining adults, but only after the breeding source is gone; traps and sprays on their own give only temporary relief.[1][3]
Where sources disagree
Season: Kentucky's fruit fly fact sheet says they are especially common in late summer and fall, while Texas A&M says indoor infestations are most frequent in summer. Both say they can turn up year round.[1][3]
Screens: Kentucky recommends tight-fitting 16-mesh screens to keep adults out, while Texas A&M notes that fruit flies are small enough to pass through window screens.[1][3]
Common questions
- Where are fruit flies coming from if I have no fruit out?
- Check drains, disposals, recycling bins, empty bottles, mops and rags, spills under appliances and loose lids on vinegar, wine or cider; any moist, fermenting film can support them.[1][3]
- What's the best fruit fly trap?
- A jar baited with a few ounces of cider vinegar and fitted with a paper funnel works well once the breeding source has been removed.[1]
- Do fruit flies bite?
- No. They are non-biting flies. The concern is that they can carry bacteria onto food.[2][3][7]
Sources
- University of Kentucky Entomology, “ENTFACT-621: Fruit Flies.” entomology.mgcafe.uky.edu/ef621 (accessed 2026-11-11)
- University of Kentucky Entomology, “ENTFACT-657: Small Flies.” entomology.mgcafe.uky.edu/ef657 (accessed 2026-11-11)
- Texas A&M AgriLife Extension, “ENTO-050: Indoor Flies and Their Control.” agrilifeextension.tamu.edu/library/insects/indoor-flies-and-their-control/ (accessed 2026-11-11)
- University of Kentucky Entomology, “ENTFACT-615: Drain Flies or Moth Flies.” entomology.mgcafe.uky.edu/ef615 (accessed 2026-11-11)
- University of California Statewide IPM Program, “Pest Notes: Fungus Gnats, Publication 7448 (August 2013).” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pnfungusgnats.pdf (accessed 2026-11-11)
- NC State Extension, “Phorid Flies.” content.ces.ncsu.edu/phorid-flies (accessed 2026-11-11)
- Applied and Environmental Microbiology, via PubMed, “Janisiewicz et al. (1999), Fate of Escherichia coli O157:H7 on fresh-cut apple tissue and its potential for transmission by fruit flies.” pubmed.ncbi.nlm.nih.gov/9872751/ (accessed 2026-11-11)
- Vector-Borne and Zoonotic Diseases, via PubMed, “Nmorsi, Agbozele and Ukwandu (2007), Filth flies (Musca domestica, M. domestica vicina, Drosophila melanogaster) and associated bacterial pathogens in Ekpoma, Nigeria.” pubmed.ncbi.nlm.nih.gov/17627427/ (accessed 2026-11-11)
- iNaturalist, “Drosophila melanogaster taxon page (order and family).” www.inaturalist.org/taxa/1409656 (accessed 2026-10-06)