Apple cider vinegar smells like fermenting fruit to fruit flies; leaving a small cup out can lure them into a simple trap

Fruit flies can appear around kitchens when ripe or fermenting food provides suitable conditions for feeding and reproduction. They may be attracted to overripe bananas, fruit peels, spilled juice and other organic material where fermentation is taking place. Their presence is therefore closely linked to the smells released as food begins to break down. Apple cider vinegar produces some of the same fermentation-related chemical cues, allowing its familiar odour to be used as a simple lure for fruit flies.

According to research published in the Journal of Insect Physiology, acetic acid, a major component of vinegar and a product associated with fermenting fruit, can influence the behaviour of fruit flies and attract them towards suitable food and egg-laying sites. Research published in the Journal of Applied Entomology similarly found that vinegar-based baits attracted spotted-wing drosophila, with traps containing acetic acid capturing significantly more flies than unbaited traps. The researchers found that vinegar's attraction is linked partly to volatile chemicals released from the bait, helping explain why the familiar smell of vinegar can draw fruit flies towards a trap.

Why vinegar catches their attention


For a fruit fly, the smell of fermentation can signal that food is available. As fruits become overripe, microorganisms break down sugars and produce a mixture of volatile compounds, including alcohols and organic acids. These odours can help flies locate food and places where they can reproduce.

Acetic acid is associated with both vinegar and fermentation, but fruit flies' response depends on its concentration and the surrounding chemical cues. Laboratory research on Drosophila melanogaster has found that low concentrations of acetic acid can attract the flies, while higher concentrations can become aversive. This suggests that fruit flies respond not simply to the presence of acetic acid, but to the concentration and combination of volatile compounds associated with fermenting food. Such cues can help them locate food sources that may also provide suitable conditions for reproduction.

Research on spotted-wing drosophila, a related species, provides further evidence for vinegar's usefulness as a lure. In field experiments, traps containing vinegar caught substantially more flies than traps without a bait. The researchers also found that combinations of vinegar and wine were more attractive than either ingredient alone, suggesting that fruit flies respond to a mixture of fermentation-related chemicals rather than to a single smell.

Turning the lure into a trap

A simple trap can be made using a small container and apple cider vinegar. Pour a small amount of vinegar into a cup or bowl and place it near areas where fruit flies are present, such as fruit bowls, compost containers or sinks. The vinegar serves as an odour-based lure, while flies that enter the container may become trapped in the liquid.

A small amount of washing-up liquid can make the trap more effective by reducing the surface tension of the liquid. This makes it harder for flies that land on the surface to remain there and escape. The trap therefore combines two simple steps: the vinegar acts as the attractant, while the liquid provides the mechanism for trapping the insects.

Another option is to cover the container with plastic wrap and make several small holes in it. The openings allow the vinegar's smell to escape and give flies a route into the container while making it more difficult for them to leave. The method is particularly useful when the flies are concentrated around a specific area of the kitchen. This does not eliminate the source of the flies, which may still be nearby in ripe or rotten fruit, garbage, juice, recycling bins or damp organic matter.

A smell-based solution, not a miracle cure

Fruit flies are able to detect chemical signals associated with fermenting food, and vinegar contains volatile compounds that can serve as similar cues. Placing vinegar in a container can therefore help attract flies to a specific location. Research published in Pest Management Science also found that spotted-wing drosophila responded to several compounds released from fermented bait, with combinations of compounds producing stronger attraction than some individual chemicals.

However, attraction varies among fly species and depends on the chemicals present in the bait. A vinegar trap can catch flies that are drawn to it, but it does not remove the food, moisture or other organic material that may be supporting an infestation.