Francis the Fly appears in Mopatop's Shop in the episode "The Fly". It interrupted Mopatop's introduction with it's loud buzz. It was having fun with both Mopatop and Puppyduck and it even answered their questions with one buzz for yes and two buzz for no. It turns out that it's friend, a frog, asked him to wait in the shop while he finished some errands. They left together to go to lunch.
The fly was not seen, only heard in the episode.