Fighter Fly

A Fighter Fly is a grinning pest that first appeared in the sewers of the original Mario Bros. arcade game. They are characterized by their ability to hop; an ability that allows them to cause trouble for Mario and Luigi.

Mario Bros. (Arcade 1983)
In Mario Bros., Fighter Flies are one of the myriad of pests that emerge from pipes to attack Mario and Luigi. They first appear in Stage Six. After a Fighter Fly emerges, it will hop across the stageâ€™s platforms. As such, Mario had to precisely time his jump when the Fighter Fly was on the ground to flip the creature over. If airborne, a Fighter Fly would not be flipped over - not even if Mario uses the POW Block. Once flipped over, Mario had to run into the insect to clear it off the stage.

Super Mario Land (Game Boy)
This time Fighter Flies were in the Birabuto Kingdom of Sarasaland, where they would once again hop towards Mario. Kumos from the Easton Kingdom attack in the same manner as Fighter Flies.

Mario & Luigi: Superstar Saga (Game Boy Advance 2003)
In this game, Fighter Flies abandoned their sewer home and migrated to Stardust Fields, the border between the Mushroom Kingdom and the Beanbean Kingdom. To attack, a Fighter Fly will hop towards Mario or Luigi and bump into the plumber. Jump to aviod their attacks.

Mario and Luigi also encountered a stronger version of the Fighter Fly, the Superfly, in the basement of Beanbean Castle

Other Names
In the Japanese version of Mario Bros., the Fighter Fly is named the Hae-San.