Unfortunately, humans in the vicinity of fly-infested horse environments suffer similarly. Houseflies, face flies, horn flies and stable flies are merely some of the species that seem to love equine flesh. Sanitation around the stables is the only effective long term approach to control of these and most other flies. Flies carry many disease agents, including eyeworms and 65 other pathogens. In recent years, new medications have made treatment of stomach bots safer and more effective than in the past.
Mosquitoes are serious pests of horses.
Many spread the viral diseases known as Western, Eastern and Venezuelan equine encephalitis. Horseflies spook horses with viscous, slashing bites and persistent blood sucking. Equine Infectious Anemia may be spread from horse to horse by this mechanism. These pests are all difficult to control. Long Range Program Arthropod parasites can't be eradicated in most horse environments.