Flies often buzz persistently around people. Understanding why they are drawn to human presence and the types of flies involved can help reduce these encounters.
Why Flies Are Drawn to You
Flies use highly sensitive sensory organs to detect various cues emitted by humans. One primary attractant is carbon dioxide, which humans exhale with every breath. Flies can sense these plumes of CO2 from a distance, signaling the presence of a potential host or food source.
Beyond breath, human bodies release odors through sweat and skin oils. Compounds like lactic acid, ammonia, and certain fatty acids found in sweat are particularly appealing to many fly species. These substances can signal moisture and nutrients that flies seek for sustenance. Body heat acts as a beacon, guiding flies closer to a warm-blooded target. Some flies may also be attracted to the salt content in human sweat, which is a necessary resource.
Flies may also land on human skin to sample the surface for nourishment. They possess chemoreceptors on their feet, which allow them to “taste” for sugars, salts, and other organic matter. This behavior is part of their search for food, moisture, or a suitable place to rest.
Common Types of Swarming Flies
Several types of flies are commonly observed swarming around humans. Gnats, often mistaken for smaller flies, are a frequent culprit, particularly drawn to moisture and the carbon dioxide in breath. They may form noticeable clouds, especially during mating swarms.
Fruit flies are another common nuisance, though they are primarily attracted to fermenting organic materials like overripe fruit. House flies, one of the most widespread species, are general scavengers attracted to a broad range of decaying matter, including food waste and animal feces, but will also investigate human skin for nutrients. While less common, certain biting flies like deer flies or black flies are directly seeking blood meals for reproduction, and they are also drawn to carbon dioxide.
Strategies to Avoid Flies
Minimizing your attractiveness to flies involves addressing the cues that draw them in. Personal hygiene can reduce the appeal of sweat and skin oils, as regular washing helps remove the compounds that flies find enticing.
Wearing appropriate clothing can also make a difference. Light-colored clothing may be less attractive to some biting flies, and long sleeves and pants provide a physical barrier. Insect repellents containing active ingredients like DEET or picaridin can effectively deter flies. Some natural repellents, such as essential oils like lavender, peppermint, or eucalyptus, may also offer protection.
Being mindful of your environment is another strategy. Avoid strong fragrances from perfumes, lotions, or hair products, as these can attract flies. Limiting outdoor activities during peak fly times, often dawn and dusk, can reduce encounters. Reducing stagnant water and decaying organic matter nearby, such as unemptied trash bins or pet waste, removes potential breeding and feeding sites that attract flies.