Flies are common insects that often become unwelcome guests in homes and businesses, due to their strong attraction to various food sources. Their presence is not merely a nuisance, as flies can carry bacteria and other pathogens, posing a hygiene concern. Understanding what draws these insects to certain substances is key to managing their populations and preventing potential contamination. This attraction stems from their biological needs for sustenance and reproduction, closely tied to chemical signals emitted by food.
Common Food Attractants
Flies are drawn to foods with easily accessible nutrients, especially those undergoing decomposition. Overripe or decaying fruits and vegetables are appealing due to their sweetness and the fermentation process they undergo. Fruit flies, for instance, are attracted to fermenting fruits like bananas, grapes, and tomatoes, and vegetables such as potatoes and onions, especially when left unrefrigerated. The breakdown of these items releases sugars and other compounds that flies can readily detect.
Beyond produce, flies show a strong preference for sugary liquids and fermented beverages. Sodas, fruit juices, wine, beer, and even vinegar attract flies with their high sugar content and the presence of alcohol or acetic acid. These liquids provide quick energy and act as signals for suitable feeding and breeding sites. Various types of flies, including house flies and blow flies, are attracted to protein-rich sources, particularly decaying meat, animal carcasses, and feces. These materials serve as food for adult flies and ideal breeding grounds for their larvae, offering a rich source of nutrients for development.
Underlying Reasons for Attraction
The attraction of flies to specific foods is driven by their chemoreception system, allowing them to detect chemical compounds released during food decomposition. Sugars, for example, are a direct source of energy, and flies possess specialized chemoreceptors that detect sweet tastes. This allows them to locate sugary substances like ripe fruits and beverages.
Fermentation products play a significant role in attracting flies. As fruits and other organic matter break down, microorganisms like yeast produce ethanol (alcohol) and acetic acid. Flies, particularly fruit flies, are highly sensitive to these volatile organic compounds (VOCs). Acetic acid, the main component of vinegar, is a strong attractant, signaling a potential caloric source. Alcohol, even at low to moderate concentrations, also attracts flies and can enhance the appeal of other food odors, influencing feeding and mating.
Flies also detect volatile compounds associated with decay, such as those released from rotting meat. These include sulfur-containing compounds like dimethyl disulfide and dimethyl trisulfide, which are strong signals for blow flies seeking oviposition sites. Moisture is another factor, essential for fly survival and for the development of their larvae. Flies rely on their olfactory receptors on their antennae to detect these chemical cues from considerable distances, guiding them to suitable food sources for consumption and reproduction.