According to Wikipedia (I'm being lazy today) Horse-fly is the most widely-used English common name for members of the family Tabanidae. Apart from the common name "horse-flies", broad categories of biting, bloodsucking Tabanidae are variously known as breeze flies, clegs, deer flies, gadflies, or zimbs. In some areas of Canada, they also are known as Bull Dog Flies. In Australia some species are known as "March flies", a name that in other English-speaking countries refers to a very different Dipteran family, the non-bloodsucking Bibionidae.
Anyway these flies bite and can bite though shirts even. But they have lovely eyes and of course the males, like us chaps everywhere are peaceful and would not even hurt a fly.