Ditzies are tiny flying creatures on Fraggle Rock. In the original sketchbook pitch for the series, the Ditzies were intended as the fourth major species living around Fraggle Rock. Ditzies are even smaller than Doozers. According to the sketchbook, "little is known of Ditzy customs as of this writing." 
While the Ditzies were dropped as a regular element before the series went to air, they finally debuted in the second season episode "The Day the Music Died." The Ditzies are discovered by Gobo Fraggle, luminous creatures who are in fact the source of all light in Fraggle Rock. The Ditzies are dying however, and their light fading causing a blackout throughout the rock and sending most of the Fraggles, Doozers, and any other life within Fraggle Rock to sleep. Gobo prevails however and discovers that music is what keeps the Ditzies alive and vibrant. Upon performing "Shine On, Shine On Me," the Ditzies recover thus awakening all life in Fraggle Rock. After the song, the Ditzies thank Gobo and the Fraggles for saving them.