Richard Deacon, a small-time criminal out on parole, was shot by the police and left for dead after his unsuccessful kidnapping attempt was foiled by Spider-Man. Stumbling into the laboratory of Dr. Harlan Stillwell (whose brother Farley created the Scorpion for J. Jonah Jameson), Deacon coerced the scientist into saving his life. Overhearing an offer Jameson made with Stillwell to fund the creation of a new super hero, Deacon insisted he be the subject of the experiment. Stillwell imprinted the genetic coding of a common fly onto Deacon, empowering him and healing him of his bullet wounds. Deacon killed Stillwell and used his newfound powers to further his criminal ambitions. He first used Jameson as bait to get revenge on Spider-Man, but his inexperience was no match for the web-slinger and he was defeated.
Sometime later, the Fly attacked Spider-Man who was handcuffed to Jameson with a bomb. The Fly hurled the two from a rooftop and left them for dead. Once freed from the shackle, Spider-Man tried to stop the Fly from stealing an art exhibit, but the villain knocked him down and escaped. Soon afterwards, however, the police caught the Fly using S.H.I.E.L.D. equipment.
Traveling to San Francisco, the Fly sought out Dr. Karl Malus, a criminally inclined scientist. Malus planned to augment Deacon's powers with a blood transfusion from Spider-Woman. The Fly attacked her unsuccessfully. Malus then suggested that he kidnap her associate, Scotty MacDowell. Spider-Woman followed the Fly to Malus's headquarters and, after a brief fight, defeated him. Afterwards, Malus used some of the Fly's DNA to temporarily mutate Scotty into the similarly powered Hornet.
The Fly subsequently battled Moon Knight, leaving the hero temporarily paralyzed, and again tried to seek revenge against Jameson and Spider-Man. Partnered with the Black Cat, Spider-Man once more defeated the Fly. Over time, Deacon's mutation increased; he grew antennae and became more fly-like in his behavior. Even his dietary tastes shifted to garbage. After escaping from a mental institution, Deacon was killed by one of the vigilantes calling themselves the Scourge of the Underworld.
