As the misses and I were sitting out Sunday evening trying to enjoy the rest of the end of the weekend, we found our stay cut short by the rapid fire bombing of horse flies.
Female horse flies feed on the blood of humans and other animals, while the males do not feed on blood. These pests can detect humans by movement, color, or carbon dioxide output. They do not feed indoors, but sometimes enter homes on accident through open windows and doors. These flies are only active during the day and are usually more abundant in the summer and around pools, lakes or other bodies of water. Horse fly females are aggressive blood feeders.
The most obvious sign of a horse fly infestation is the bothersome and painful biting caused by the adult female flies and the symptoms and reactions to their bites.
Similar to other blood-sucking insects such as mosquitoes for example, female horse flies use both chemical and visual cues to locate hosts. Carbon dioxide expelled by warm-blooded animals provides a long-range cue to attract flies from a distance, while visual cues such as motion, size, shape and dark color function to attract horse flies from shorter distances.
They rarely bite near the head. Horse flies have a range of hosts that include mammals of almost all sizes, livestock, humans, pets and birds. Should a female horse fly be interrupted when attempting to feed, they will fly off but quickly return to bite again, or go to another host to consume a complete blood meal.
Do horse flies spread disease? Investigators have isolated many viruses, bacteria and protozoa from the sponge-like female mouthparts and their digestive system, but no studies to date show conclusive evidence that horse flies are capable of transmitting diseases to humans.
Disease transmission to livestock is another matter. Adult flies may pass a number of disease agents and nematode parasites to animals. Equine infectious anemia (EIA), sometimes referred to as swamp fever, occurs in the southeastern United States and is mechanically transmitted to horses and other equines by horse fly bites. Symptoms in animals include lethargy, weight loss and sometimes death.
University of Arkansas, United States Department of Agriculture and County Governments Cooperating. The Arkansas Cooperative Extension Service offers its programs to all eligible persons regardless of race, color, sex, gender identity, sexual orientation, national origin, religion, age, disability, marital or veteran status, genetic information, or any other legally protected status, and is an Affirmative Action/Equal Opportunity Employer.
 As for control, insect repellents are helpful but even the best repellents are not overly effective. A better prevention option is to clothe and protect exposed parts of the body to reduce the likelihood of horse fly bites.
If you should have any questions concerning horse fly control, please feel free to contact the Phillips County Extension Office at 870-338-8027