Horse flies are notorious for their painful bites, turning a pleasant outdoor experience into an itchy ordeal. Unlike mosquitoes that stealthily sip blood, female horse flies slice into skin to lap up blood, causing considerable discomfort. But what exactly makes humans a target for these persistent pests? Understanding what attracts horse flies is the first step in effectively avoiding them.
Several factors make humans attractive to horse flies, primarily catering to the female’s need for blood to nourish their eggs.
Visual Cues: Movement and Dark Colors
Horse flies rely heavily on sight to locate their prey. They are particularly drawn to movement and contrasting dark colors against lighter backgrounds. This is why people wearing dark clothing in sunny, open areas often find themselves swarmed by these flies. The movement of a person walking or swatting also catches their attention, signaling a potential blood source.
Carbon Dioxide and Breath
Like many blood-feeding insects, horse flies are attracted to carbon dioxide (CO2), which humans exhale with every breath. While not as sensitive to CO2 as mosquitoes, it still plays a role in their host-seeking behavior. The plume of CO2 we breathe out can act as a long-range attractant, drawing them closer from a distance.
Body Heat and Odor
Horse flies are also sensitive to body heat. Warm-blooded animals, including humans, emit heat that horse flies can detect. Additionally, body odor, particularly sweat, can be a significant attractant. The components of sweat, such as lactic acid and ammonia, are known to lure various fly species, including horse flies. This explains why horse flies are often more bothersome during physical activity when we sweat more and our body temperature rises.
Moisture and Water Sources
While not directly attracting them to humans, the presence of water sources nearby increases the likelihood of encountering horse flies. Horse flies breed in damp environments, including marshes, ponds, and even wet soil. Being near these areas means being in closer proximity to horse fly populations, increasing the chances of being bitten.
Minimizing Attraction
Knowing what attracts horse flies allows for strategic avoidance and preventative measures.
- Wear light-colored clothing: Opt for white or light-colored clothing to reduce your visual appeal to horse flies.
- Reduce movement: Sudden movements attract attention. Try to move calmly in areas with horse flies.
- Use insect repellent: Repellents containing DEET or permethrin can mask your scent and make you less attractive. Apply repellent to exposed skin and treat clothing with permethrin for added protection.
- Avoid peak season and habitats: Horse fly activity is highest during warmer months and near damp, grassy areas. Being aware of these peak times and locations can help you avoid them.
By understanding the factors that draw horse flies to humans, you can take informed steps to minimize your attractiveness and enjoy the outdoors with fewer irritating bites. While completely eliminating horse flies might be impossible, reducing your appeal significantly decreases the chances of becoming their next meal.
