A purple fly is a rare kind of fly that roams around the Smurf Forest. It is the carrier of a disease that affects Smurfs by biting them in the tail, causing them to change into a Purple Smurf. Purple flies are usually rendered harmless when they inhale the pollen of a tuberose blossom, which makes them sneeze before turning blue.
The purple fly makes its only appearance in the cartoon show episode "The Purple Smurfs", and is based on the Bzzz Fly from the comic book story "The Black Smurfs", which according to some Smurfs in "The Egg And The Smurfs" was the origin for Grouchy's behavior.
The purple fly makes an appearance in the homebrew videogame Smurf Challenge as the Bzzz Bzzz Fly.