Horse-flies or horseflies (for other names, see common names) are true flies in the family Tabanidae in the insect order Diptera. They are often large and agile in flight, and the females bite animals, including humans, to obtain blood. They prefer to fly in sunlight, avoiding dark and shady areas, and are inactive at night. They are found all over the world except for some islands and the polar regions. Both horse-flies and botflies (Oestridae) are sometimes referred to as gadflies.Adult horse-flies feed on nectar and plant exudates; the males have weak mouthparts and only the females bite animals...