Flies frequently land on humans, a common occurrence. This behavior stems from specific biological needs and the signals our bodies inadvertently send. Understanding these interactions can shed light on why these insects are drawn to us.
Why Flies Land on You
Flies are attracted to humans for several reasons, primarily seeking sustenance, moisture, and warmth. They possess sensory organs that detect various cues emitted by the human body and its environment. These cues include carbon dioxide, which flies can detect from a distance, signaling a potential host or food source.
Body heat also attracts flies, as they are cold-blooded and rely on external sources to regulate their temperature. Exposed skin, being warmer, particularly draws their attention. Human sweat is a mixture containing water, salts, and organic compounds like lactic acid and ammonia, all appealing to flies. They can absorb these salts and moisture directly from the skin.
Flies also detect natural body odors, which are produced by bacteria on our skin and the breakdown products of various bodily secretions. Their feet, equipped with chemoreceptors, allow them to “taste” surfaces they land on, quickly assessing if something is an edible substance. This enables them to find and consume residual food particles, oils, or even shed skin cells on our bodies. General house flies are opportunistic feeders drawn to a wide range of organic matter.
Potential Health Implications
Flies can pose health risks because they frequently interact with decaying matter, waste, and feces, picking up microorganisms. When a fly lands on human skin, it can mechanically transfer these pathogens from its body, legs, or mouthparts. House flies carry pathogens, including bacteria, viruses, fungi, and parasites.
Over 100 pathogens have been associated with house flies, and they are mechanical vectors for more than 65 infectious diseases in humans. Examples include common bacteria like Escherichia coli and Salmonella, which can cause foodborne illnesses. Flies can deposit these agents onto skin or open wounds, allowing bacteria to enter the body. While the risk from a casual landing on intact skin is generally low for healthy individuals, it increases if there is an open wound.
Simple Ways to Keep Flies Away
Preventing flies from landing on you involves minimizing attractants. Maintaining personal hygiene reduces body odors, sweat residue, and other organic compounds on the skin. Regular bathing and changing into clean clothes can make you less appealing to flies.
Keeping food covered, especially during outdoor meals or in kitchens, reduces fly attraction. Promptly cleaning up spills and crumbs eliminates potential food sources. Using screens on windows and doors prevents flies from entering indoor spaces. Avoiding scents from perfumes, lotions, or heavily scented soaps can help, as some inadvertently mimic attractive odors. Ensuring trash cans are covered and regularly emptied, particularly those containing food waste, removes breeding grounds and attractants.