Fruit Flies

This page is about the fruit fly, family Drosophilidae — the fly commonly called the vinegar fly or pomace fly in the scientific literature, and the one behind almost every “tiny flies in my kitchen” problem. Two other small flies get mistaken for it often enough that extension services write about the distinction directly, and this page covers that too, in its own section below.

Source elimination comes before anything else on this page, because every source consulted agrees on the order: University of Kentucky Extension states that once a structure is infested, all potential breeding areas must be located and eliminated, and that unless the breeding sites are removed, the problem will continue no matter how often insecticides are applied to the adults.

What It Is

University of Kentucky Extension: Adults are about 1/8 inch long and usually have red eyes. The front portion of the body is tan and the rear portion is black. Colorado State University Extension gives a closely matching description: Small fruit flies are small flies, approximately 3 mm (1/8) long. They are stout bodied and with a tan-colored head and thorax. The abdomen is darker, often with bands. Most have bright red eyes.

On exact size, the sources do not all agree, and each figure is reported here as its own source states it. University of Kentucky Extension and Colorado State University Extension both give roughly 1/8 inch for the adult. Iowa State University Extension states fruit flies are small, red-eyed, 1/4 inch long flies. University of Maryland Extension splits the difference by life stage rather than disagreeing outright: it gives 1/8 inch for the adult and states the larvae are whitish, 1/4 of an inch long, eyeless and legless, and taper towards the head. No figure is corrected against another here.

On reproduction, the University of Kentucky Extension figures are specific: given the opportunity, they will lay about 500 eggs, and the entire lifecycle from egg to adult can be completed in about a week. University of Maryland Extension gives a close figure for the larval stage alone — the larvae feed for 5 to 6 days and then crawl to drier areas to pupate, with the entire life cycle taking 8 to 10 days.

If It Is Not a Fruit Fly

Texas A&M AgriLife Extension covers three other small flies commonly mistaken for fruit flies indoors, and gives a working test for each:

• Drain flies, also called moth flies. Texas A&M AgriLife Extension: Drain flies (Family Psychodidae) are also called moth flies because of their fuzzy, moth-like appearance — dark gray to black, densely hairy, wings held flat or roof-like over the body at rest. Colorado State University Extension breeds moth flies to the same plumbing habitat: Moth flies (Psychodidae family) also may be found indoors and similarly are associated with plumbing, developing on the bacterial gel that sometimes coats the interior of pipes.
• Phorid flies — also sometimes called “drain flies,” a naming collision worth flagging rather than resolving. Texas A&M AgriLife Extension: Phorid flies (Family Phoridae) are another fly found in homes and, even more commonly, in commercial buildings, about the same size as a fruit fly but with a hump-backed appearance. Colorado State University Extension calls this same family by a different name: Most similar in general size and body shape are phorid flies (Phoridae family), sometimes known as drain flies — the same common name Texas A&M attaches to the Psychodidae instead. The common name “drain fly” is not used consistently between these two sources; the family name is the reliable identifier, not the common one.
• Fungus gnats. Texas A&M AgriLife Extension: Fungus gnats (Families Mycetophilidae and Sciaridae) are very small (1/16 to 1/8 in, 1.5 to 3 mm), slender flies with clear or dark wings, mosquito-like with long slender legs and bead-like antennae, and states directly that unlike mosquitoes, fungus gnats do not bite. Colorado State University Extension places their breeding site outside the drain entirely: Fungus gnats also may occur indoors and are associated with the potting soil of houseplants.

If small flies are breeding in a houseplant’s soil rather than a drain or ripening produce, the sources point to a fungus gnat, not a fruit fly, and the control step is different — drying out the soil, not treating a drain. See also our house flies page for the larger filth fly that mechanically transmits contamination rather than breeding in drains, and our cluster flies page for the slow, dark, much larger fly that shows up at windows in fall — neither is the small red-eyed fly this page covers.

Where They Breed

University of Kentucky Extension: fruit flies are especially attracted to ripened fruits and vegetables in the kitchen, but they also will breed in drains, garbage disposals, empty bottles and cans, trash containers, mops and cleaning rags. All that is needed for development is a moist film of fermenting material.

Iowa State University Extension names the most commonly overlooked site directly: The most likely of such sites in the home is a slow-moving or seldom-used sink, bathtub, shower, or floor drain in which a layer of slime (gelatinous film) has built up above the water line.

• Produce. University of Kentucky Extension names tomatoes, melons, squash, grapes and other perishable garden produce, plus rotting bananas, potatoes and onions bought at a grocery store.
• Containers. University of Maryland Extension states to rinse and drain bottles and cans that are to be recycled, and to squeeze mops thoroughly and dry them, since a damp mop or towel can carry enough food and moisture to complete development.
• Home fermentation. University of Kentucky Extension states that people who can their own fruits and vegetables, or make wine, cider or beer, should ensure containers are well sealed, or fruit flies will lay eggs under the lid.
• From outdoors. University of Kentucky Extension states the adults can also fly in from outside through inadequately screened windows and doors.

Source Elimination and Prevention

University of Kentucky Extension is direct about what actually ends an infestation: Once a structure is infested with fruit flies, all potential breeding areas must be located and eliminated. Unless the breeding sites are removed or cleaned, the problem will continue no matter how often insecticides are applied to control the adults. The same source notes breeding sites which are inaccessible — garbage disposals and drains — can be inspected by taping a clear plastic food storage bag over the opening overnight; if flies are breeding there, the adults will emerge and be caught in the bag.

• University of Kentucky Extension: produce which has ripened should be eaten, discarded or refrigerated, and cracked or damaged portions cut away and discarded.
• University of Maryland Extension: keep fruit stored in the refrigerator, and rinse recycling before it accumulates.
• University of Kentucky Extension: Windows and doors should be equipped with tight-fitting (16 mesh) screens to help prevent adult fruit flies from entering from outdoors.

Drain Treatment

On bleach and ammonia, the sources are direct rather than silent about a common assumption. Iowa State University Extension states plainly: There is no benefit to treating drains with bleach or ammonia.

What the same source recommends instead: Clean slow-moving drains with a stiff brush or other tool. Drains that cannot be scrubbed can be rinsed with water under high pressure or "sterilized" by slowly pouring boiling water down along the sides of the drain pipe. It names one further option — a bacterial drain treatment that biodegrades the organic matter — with the instruction to follow label directions carefully for best results.

Traps

Two homemade trap designs are given across the sources, and neither is presented as superior to the other.

• The funnel-jar method. University of Kentucky Extension: a paper funnel (rolled from a sheet of notebook paper) into a jar which is then baited with a few ounces of cider vinegar. Place the jar trap(s) wherever fruit flies are seen.
• The dish-soap method. University of Maryland Extension describes a different mechanism using the same bait: pour apple cider vinegar into the bottom of a glass jar and add a drop of dish soap, cover the top with plastic wrap or a small plastic bag, and secure the plastic tightly around the rim with a rubber band. Then poke a tiny hole in the plastic to allow the flies to enter but not escape.

On insecticide, University of Kentucky Extension is specific about sequencing: after the source of attraction and breeding is eliminated, a pyrethrum-based, aerosol insecticide may be used to kill any remaining adult flies in the area — spraying is a cleanup step after source removal, not a substitute for it.

Questions

Sources

Every factual claim above names the source it rests on, in the sentence that makes it or in the text immediately adjacent to it, and every source named is listed below. Framing, ordering and emphasis are our own judgement and are not a finding of any source. Where sources give different figures or use a common name differently, both are reported and attributed rather than resolved into one answer.

1. University of Kentucky, Martin-Gatton College of Agriculture, Food and Environment. Fruit Flies, ENTfact-621. Accessed 1 September 2026. https://entomology.mgcafe.uky.edu/ef621
2. Colorado State University Extension. Small Fruit Flies (Vinegar Flies), Colorado Insect of Interest. Accessed 1 September 2026. https://wci.extension.colostate.edu/wp-content/uploads/sites/14/2017/03/FruitFlies.pdf
3. Iowa State University Extension and Outreach, Yard and Garden. Fruit, Vinegar, and Pomace Flies. Accessed 1 September 2026. https://yardandgarden.extension.iastate.edu/encyclopedia/fruit-vinegar-and-pomace-flies
4. Texas A&M AgriLife Extension Service. Indoor Flies and Their Control, ENTO-050. Accessed 1 September 2026. https://agrilifeextension.tamu.edu/wp-content/uploads/2023/08/ENTO-050-indoor-flies-and-their-control.pdf
5. University of Maryland Extension. Fruit Flies. Accessed 1 September 2026. https://extension.umd.edu/resource/fruit-flies