When flies are this small, you’ll have to trust us that, like all adult flies, fruit flies only have two wings (Diptera = di + ptera, which means wing). But you’ll notice fruit flies because of their activity—hovering over fruit—not their looks. Up close you might notice red eyes or dark eyes, and minor difference in color and size, but here are the two you'll most likely see:
Red-Eyed Fruit Fly: tan to beige color; red-eyes; hovering flight (1/16 inch; 2 mm).
Dark-Eyed Fruit Fly: dark-gray to black; rests on wall; hovering flight (larger than red-eyed fruit fly: 1/8 inch; 3 to 4 mm).
As with all flies, their hatched eggs become larvae known as maggots: eyeless and legless. Well-fed maggots become brown, cigar-shaped pupae that you’ll likely not see.
Should I Worry About Fruit Flies?
While we are never sure where a fruit fly’s feet have been, there has not been any evidence of them spreading diseases—unlike house flies. However, unchecked, they can definitely reduce food quality, spoil a drink, and be quite annoying! Clouds of fruit flies really detract from the pleasure of preparing and eating a meal, or enjoying a glass of wine. Thankfully, they can be reduced and prevented.
The invasive Spotted Wing Drosophila, an outdoor fruit fly, is a serious pest of fruit. Unlike other fruit flies, which lay their eggs on past ripe or rotting fruit, they lay their eggs inside fresh fruit, often before harvest.
Why Do I Have Fruit Flies?
One word: Decay. Not fruit. Their larvae need yeast created by fermentation, such as found on ripening fruit.
Dark-eyed fruit fly larvae feed on yeast found in decaying plant and animal material, and are commonly associated with wet food and drink spillage in restaurants, coffee shops, and bars.
Red-eyed fruit fly larvae feed on yeast found in fermenting fruit, including banana peels, onions, tomatoes and just about any perishable produce. Larvae can also breed in food or drink-soaked cloth items, like mop heads and dish rags. In restaurants they use sugar sources like soda fountains and beer taps. Fruit flies often come into your kitchen as eggs or larvae on store-bought and homegrown produce. They don’t just appear, unless an outdoor population has open access.
Dark-eyed fruit fly pupae attached in the corner of a sink. Photo: NYSIPM.
With the large amount of feeding and breeding options in grocery stores and farmer’s markets, fruit flies are a common home pest. Adult females lay eggs on the surface of food their larvae will later eat. Eggs hatch, larvae feed and pupate, and new adults emerge. This life cycle can take place in ten days at optimum temperatures (non-refrigerated food), and one female can lay as many as 500 eggs.
How Do I Get Rid of Fruit Flies?
Always consider the source. Fruit flies primarily enter homes on fruits and vegetables.
Washing fruits and vegetables and keeping them stored properly is key. Check and store, discard or clean anything that could remain a breeding site. As long as breeding conditions linger (ripe, fermenting, decaying food and damp cloths that have come in contact with those foods) the fruit fly life cycle continues. Wash bins where fruit and vegetables are stored, and see that wet rags and mops can dry fully. Empty garbage and kitchen compost often, and rinse well. It also helps to rinse items to be recycled and to keep recycling bins clean.
Vinegar or Juice-Baited Traps
You can use their interest in fermenting food to your advantage by using bait traps. Small vinegar traps with holes in the top are available for purchase or can be made at home to attract and capture fruit flies.
A homemade fruit fly trap baited with banana, vinegar, and yeast. Photo: NYSIPM.
From Fruit Flies, Vinegar Flies, and Pomace Flies (pdf) - "If desired, a simple trap* can be made using a jar and funnel. To make a paper funnel, roll a piece of paper into a wide cone and tape it so it has a small opening at the bottom, of less than a quarter inch or just a few millimeters. In the jar, put any one of the following as bait: a bit of ripe or over-ripe banana sprinkled with yeast, a piece of banana peel, part of a ripe peach or tomato, etc. Place the funnel into the jar so that the tip does not touch the bottom of the jar or the material, and use tape to seal the funnel to the jar. Check the trap daily for adults, and kill or discard them or release them outdoors. An easy way to kill the flies is to place the trap in the freezer overnight; the funnel can be covered, folded over (if paper) or the trap can be enclosed in a bag to prevent any flies from escaping before they have frozen. The bait material in the trap should be replaced every few days, to prevent new larvae from developing.
*HOME REMEDIES -Mentions of these remedies are not endorsements by Cornell University of any product or procedure. They are not recommendations for use, either express or implied. Neither Cornell University, nor its employees or agents, are responsible for any injury or damage to person or property arising out of the use of this information."