Flies persistently buzzing around or landing on you is a common, often frustrating experience. This phenomenon has clear scientific explanations rooted in their sensory biology and behavioral ecology, demystifying why these tiny insects seem so intent on sharing your personal space.
Why You Attract Flies
Humans release cues that flies find highly attractive. One primary attractant is carbon dioxide (CO2), which we continuously exhale. Flies possess specialized receptors, such as those involving Gr21a and Gr63a proteins, that enable them to detect even subtle changes in CO2 concentrations, guiding them toward potential hosts or food sources.
Our body heat also serves as a beacon for flies, as they are cold-blooded and seek warmth for their physiological processes. The hotter a person is, particularly if they have just showered, the more appealing they become. The various scents emanating from our skin, including components of sweat like lactic acid and carboxylic acid, as well as natural skin oils, are very enticing.
Flies are opportunistic feeders; even microscopic food particles or residues on skin or clothing can be a draw. They are also attracted to moisture, such as sweat, which provides essential salts and water. These combined sensory signals make humans attractive targets for flies.
Understanding Their Persistent Behavior
Once attracted, flies exhibit persistent behavior due to their innate drives for exploration and resource acquisition. Flies often seek a stable surface to rest, and a human can serve as a convenient, warm, moving platform. This behavior is part of their continuous search for food, moisture, or suitable sites for laying eggs.
Common house flies (Musca domestica) are scavengers with a keen sense of smell and complex eyes. They constantly hunt for nourishment, including salts, dead skin cells, and oils on our skin. When a fly lands, it “tastes” with its feet, which are covered in taste receptors, to quickly determine if a surface is edible.
Flies may also vomit digestive enzymes onto solid surfaces, including skin, to liquefy potential food before sucking it up with their proboscis. Their erratic flight patterns, often seen as persistence, are also a defense mechanism, making them difficult for predators, including humans, to catch. This combination of resource-seeking and evasive maneuvers explains their persistent return despite attempts to shoo them away.
Simple Ways to Discourage Flies
Minimizing your attractiveness to flies involves addressing the cues that attract them. Maintaining good personal hygiene by keeping skin clean and dry can reduce appealing scents and moisture. Showering removes sweat and oils, though some lingering organic compounds may remain.
Lighter clothing colors may also be less attractive to some insects. Avoiding strong, sweet, or fruity perfumes and lotions can help, as these scents can inadvertently mimic attractants.
Controlling your immediate environment is also effective; this includes covering food, promptly disposing of trash, and ensuring windows and doors have well-fitted screens to prevent entry. If a fly does land, gently shooing it away is often sufficient, as repeated swatting can sometimes make them more evasive. Certain natural scents like lemongrass, eucalyptus, peppermint, and bay leaves can also act as deterrents.