The common European Cleg is a large, black/blue-black blood-sucking 'horsefly' of the family Tabanidae. It is commonly referred to as a Gadfly in the United States. They are powerful flyers, and the females are furnished with a lancet-like proboscis which can pierce the thickest skin.

Common European Cleg (Gadfly)

The common European Cleg is a large, black/blue-black blood-sucking 'horsefly' of the family Tabanidae.…

"Lancet arches, with centers outside the arch." — The Encyclopedia Britannica, 1910

Lancet Arch

"Lancet arches, with centers outside the arch." — The Encyclopedia Britannica, 1910

"Two-light lancet." —D'Anvers, 1895

Two-light lancet

"Two-light lancet." —D'Anvers, 1895