From the Super Mario Wiki
Flutters (also called Wiggler Flies, Flying Wigglers, or Butterflies) are butterfly sub-species of Wigglers that first appeared in Super Mario World 2: Yoshi's Island. When hit, they act like the normal Wiggler, getting enraged. Instead of flying around aimlessly, though, they charge straight for the Yoshi that hit them.
Super Mario World 2: Yoshi's Island / Yoshi's Island: Super Mario Advance 3
Flutters, known in this game as Wiggler Flies, are only seen in "GO! GO! MARIO!!". Just before the goal, a swarm of them appear over a flat turf, they fly up and down and charge towards Yoshi if an egg is thrown at them or jumped on. They are defeated if hit by Yoshi's tongue or a Ground Pound.
A Wiggler Fly, under the name Flying Wiggler, appears in Tetris Attack, which depicts it as a friend of Yoshi rather than an enemy. Flying Wiggler is playable in Time Trial mode, and can be fought and rescued on the Flower Stage in the main Vs. Com mode. In the SNES version, it is paired with the similarly-themed Eggo-Dil.
Yoshi's New Island
In volume 14 of the Super Mario-Kun, a Flutter gets infuriated after Mario plucks a flower off of it.
Mario Party series
Mario Party 5
Mario Party Advance
An individual Flutter also appears in Mario Party Advance, where she resides on the third floor of the Mushroom Condo. Two of the game's quests directly involve her. In one (Hearts A-Flutter), Flutter tells the player that she has a crush on Mr. I, and the player has to tell him that she loves him, as she is too shy. However, after learning that he said no, she still gives the player a Gaddget, Love Me Not. The other involves the lovestruck Petal Guy getting the player to deliver her a love poem (Blossom of My Heart), but, upon arriving at the condo, Petal Guy arrives and confesses his love to Flutter, but she doesn't understand what he is saying and leaves. The ending says that Flutter continues to search for a boyfriend.
Mario Party 6
Flutters reappear in Mario Party 6, as well as the Flutter Orb which retains the same affects.
Mario Party 7
Mario Party 8
Flutter also makes several cameos in Mario Party 8. It can be found in the minigames Specter Inspector as one of the hiding enemies (it is found in the piano), Moped Mayhem as a racer, and in the minigame contest Test for the Best, holding the 4,000 points sign.
Mario Party: Island Tour
Flutter appears in Mario Party: Island Tour for the Nintendo 3DS. On the Star-Crossed Skyway board, Flutter appears in the first, second, and last Star Stages. It gives out ten Mini Stars to the player who reaches it. It retains its updated nose from Paper Mario: Sticker Star.
Super Mario Advance 4: Super Mario Bros. 3
Flutters were originally going to appear in World-e of Super Mario Advance 4: Super Mario Bros. 3, but were left unused likely due to the discontinuation of the e-Reader. They were to have the same behavior to that in Super Mario World 2: Yoshi's Island.
Mario Power Tennis
Paper Mario: Sticker Star
Flutter makes its debut in the Paper Mario series in Paper Mario: Sticker Star as Wiggler's fully grown and true form. Flutter will offer to fly Mario and Kersti out to Bowser's Castle. He also refers to himself as "grown up". In this game it appears with the brown nose of a Wiggler rather than the usual pink nose.
Mario Golf: World Tour
Puzzle & Dragons: Super Mario Bros. Edition
Flutter appears as an enemy and ally alongside a Flame Chomp and it's typing is Fire and Light.
Super Mario Maker
Although Flutters themselves don't appear in Super Mario Maker, the player can place wings on Wigglers, making them act similar to Flutters.
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