Gadfly (mythology)

The gadfly, a type of fly plaguing cattle, typically ones belonging to either the family Tabanidae (horse-flies) or the family Oestridae (bot flies), appears in Greek mythology as a tormenter to Io, the heifer maiden. Zeus lusts after Io and eventually turns her into a white heifer to hide her from his jealous wife, Hera. Hera is not fooled, and demands Io as a gift from Zeus. She then sends Argus, the 100-eyed monster to guard Io, and later sends the gadfly to torment and sting Io, forcing her to wander farther and farther away from home.

The gadfly also plays a role in the myth of how Bellerophon loses Pegasus. Bellerophon attempts to ride Pegasus to the top of Mt. Olympus. Zeus is enraged by the human's attempt to ascend to the home of the gods. He sends a gadfly to sting Pegasus. The winged horse is startled and he rears backward. Bellerophon loses his grip and falls back to Earth. Athena spares his life by causing him to land on soft ground, but he becomes blind and wanders the earth until he dies, being hated by men and Gods. Bellerophon never finds Pegasus again.