Horse flies likely received their common name because they are notorious pests of horses and other mammals. They are commonly found in both suburban and rural areas near bodies of water, which serve as breeding sites, and where mammal hosts are most abundant.
Adult horse flies are fast, strong fliers and capable of flying for more than 30 miles, though they generally do not disperse widely. They most often attack moving and dark objects. Horse flies often rest on paths and roads, especially in wooded areas, where they wait for potential hosts. Horse flies are attracted to light and will sometimes congregate at windows
Horse flies are typically woodland or forest dwellers. Species usually feed during full daylight and are most evident on windless, hot, sunny days. In general, larvae develop in wet soil close to bodies of water.