Being swarmed by small flying insects is a common and often irritating outdoor experience. These persistent aerial escorts, commonly referred to as gnats, are typically tiny, non-biting flies that hover in clusters, particularly around people. While their presence can be bothersome, understanding the science behind their behavior can clarify why these insects seem to take such a keen interest in human activity. The interaction between gnats and humans involves a combination of the insects’ natural instincts and the various signals our bodies emit.
Understanding Gnat Swarms
Gnat swarming is a widespread behavior among many species of small flies. This aerial congregation serves several biological purposes. A primary reason for these swarms is mating rituals, where male gnats gather to attract females for reproduction. Swarms also provide safety in numbers, making individual gnats less vulnerable to predators. This natural tendency to form groups is a fundamental aspect of their life cycle.
Why You Attract Gnats
Humans inadvertently produce a variety of cues that are attractive to gnats, drawing them in close proximity.
One significant attractant is the carbon dioxide (CO2) we exhale. Gnats possess specialized receptors that detect CO2, an important signal indicating a potential food source. This sensitivity often leads them directly towards our faces, the primary source of the gas.
Moisture and sweat also play a significant role in attracting gnats. These insects are consistently searching for sources of moisture and salt, both of which are readily available in human sweat and tears. The skin’s microbiome metabolizes amino acids, fatty acids, and salts from sweat glands, releasing small molecules like L-(+)-lactic acid and ammonia, which further enhance attraction. Gnats are drawn to these secretions, making areas like the face, where sweat and tears accumulate, particularly appealing.
Body heat is another compelling attractant. Human bodies emit warmth, and gnats are sensitive to temperature fluctuations. They can detect even subtle changes in thermal energy, guiding them toward warm-blooded targets. This thermal signature, combined with moisture and CO2, helps gnats locate individuals.
Beyond natural bodily outputs, various scents can also draw gnats. Both natural body odors and artificial fragrances in products like perfumes, lotions, and shampoos can be attractive. Gnats are particularly fond of sweet and fruity smells, common in many personal care items. Avoiding such fragrances can help reduce their attraction.
The color of clothing can also influence gnat attraction. Research indicates that gnats are drawn to darker colors, especially black and blue. This attraction is likely due to how these colors absorb light and create a contrast against their surroundings, making them more visible to the insects. Darker clothing also tends to absorb more heat, which can make a person more noticeable to heat-seeking insects.