Fearless Fly was the back-up feature on Hal Seeger's ABC series, Milton the Monster. In fact, Milton's creator, Professor Weirdo, was Fearless' nemesis.
Unfortunately, all we have now is this intro:
Seeger, of course, didn't have the market cornered on insect superheroes. Marvel Comics was home to Ant-Man & the Wasp, and Hanna-Barbera introduced Atom Ant in 1965. And, then, there was the Fly & Flygirl at Archie Comics. In comparison, Fearless must've felt like a winged Rodney Dangerfield, getting no respect.