Note:  Do not rely on this information. It is very old.

Gad Flies

Gad Flies, a family known as the Tabanidae, belonging to the order Diptera or true flies; the females of this family are parasites, and live on the blood of various mammals; to obtain this they pierce the skin of the animal with a tubular proboscis and then suck the blood. The bite is painful, but more serious damage than this local irritation is caused by the spread of diseases which result from their attacks; thus the cattle disease known as anthrax is believed to be largely spread by the distribution of the bacillus (Bacillus anthracis) by gad flies. The largest English species is Tabanus bovinus.