Often considered pests for the bites that many inflict, they are among the world’s largest true flies. They are known to be extremely noisy during flight. They are also important pollinators of flowers, especially in South Africa. Tabanids occur worldwide, being absent only at extreme northern and southern latitudes. Flies of this type are among those known sometimes as gadflies, zimbs or clegs. In Australia, they are known as “march flies”; elsewhere this term refers to the unrelated dipteran family Bibionidae.