The Four Fantastic Flies of Famathria, each bigger and more succulent than the last, was said to be a legend fabricated by a race of toad creatures who once lived somewhere beyond the oceans of the world. Seafarers report that these toads were ugly, cantankerous, and eternally hungry. Like most legends, the tale of the Four Flies has its roots in fact. Circa 671 GUE, a flyswatter was used as a ceremonial object involving the Four Flies. Also four flies matching that description were known to exist in the Eastlands in 883 GUE (one was found in the parapet of Flatheadia Castle, another in the Great Underground Savannah, another inside a trunk in Megaboz's House in the Fublio Valley, and the last at the Frigid River Delta), but upon being captured by the First Dungeon Master, were fed to Otto the Toad in exchange for his spyglass.

SOURCE(S): Zork Zero