Flies buzzing around can be a common and often irritating experience. These small insects, despite their size, display a persistent interest in humans. Understanding the biological reasons behind this behavior can provide insights into what makes us appealing to them. While their presence might seem random, it is often driven by specific cues our bodies naturally emit.
What Draws Them In?
Flies are equipped with highly sensitive sensory organs that detect various compounds humans release. One significant attractant is carbon dioxide (CO2), which humans exhale. Many fly species, including common house flies and gnats, use CO2 as a primary signal to locate potential food sources or hosts. Their antennae possess specialized receptors that can detect even small fluctuations in CO2 levels, guiding them towards us.
Body heat also plays a role in attracting flies. Humans are warm-blooded, and the warmth radiating from our bodies can be detected by certain fly species. Moisture, particularly from sweat, is another strong attractant. Sweat contains water, salts, proteins, carbohydrates, and other chemicals that flies can consume for sustenance. Flies can lick these secretions from our skin, treating them as a source of nutrients.
Our skin also produces oils and harbors bacteria that generate specific odors. These odors, including lactic acid and carboxylic acids, can be highly appealing to flies. The composition of these skin odors varies among individuals due to genetics, diet, and daily activities, which can explain why some people seem to attract more flies than others. These combined sensory cues signal a potential meal or suitable environment for various fly species.
Common Culprits
Several common fly species are frequently observed around humans, each with distinct preferences. House flies (Musca domestica) are general scavengers attracted to a wide range of organic matter, including decaying food, garbage, and human excretions. They are drawn to the warmth, moisture, and various organic compounds on human skin, often landing to sample secretions like sweat and oils. House flies have sponging mouthparts, allowing them to liquefy and then suck up these surface nutrients.
Fruit flies, often identified by their small size and red eyes, are primarily attracted to fermenting fruits, vegetables, and sugary liquids. They may hover around individuals who have consumed sugary drinks or have sweet-smelling personal care products, as these scents mimic their preferred food sources. Fruit flies are typically found near kitchens or areas where ripe produce is present.
Gnats, a category encompassing various small flies, are also drawn to humans. Many gnat species are attracted to carbon dioxide, body heat, and moisture, similar to house flies. They are often observed near faces, seeking the moisture and salts in sweat, tears, or the mucus around eyes and noses. Fungus gnats thrive in damp environments like moist soil in potted plants, but may still be attracted to human exhalations.
Keeping Flies Away
To reduce the likelihood of flies being attracted to you, several practical measures can be employed. Maintaining good personal hygiene is a primary step, as regular bathing helps minimize body odors, sweat, and skin oils that attract flies. Avoiding strong, sweet-smelling perfumes, lotions, or hair products can also be beneficial, as these can mimic the fermented scents that appeal to certain fly species like fruit flies and gnats.
Using fans, especially when indoors or in a confined outdoor space, can disrupt fly activity. The airflow makes it difficult for flies to fly and detect scent trails, effectively deterring them. When outdoors, clothing choices can also play a role. Light-colored clothing may be less attractive to some insects compared to darker colors. Covering exposed skin with long sleeves and pants can also create a physical barrier against landing flies.
Beyond personal habits, managing your immediate environment is important. Promptly cleaning up food spills, especially sugary or fermenting substances, removes potential attractants. Regularly emptying and cleaning trash cans, particularly those containing organic waste, eliminates breeding grounds and food sources. Ensuring windows and doors have tight-fitting screens can prevent flies from entering indoor spaces.