From the Super Mario Wiki, the Mario encyclopedia

"In Super Mario 64, there are a few stages (as well as outside Peach's Castle) where there are butterflies flying around. When Mario punches one of them, one of two things will happen: The butterfly will either turn into a 1-Up Mushroom or become a large metal ball and chase Mario until it hits him, or hits something in its way."

Is this information true? I've punched a lot of butterflies, but nothing happens. --King Bean (talk ~ contribs) 06:23, 5 May 2010 (EDT)

Completely false. Hello, I'm Time Turner.
Wait, never mind. It's true. --King Bean (talk ~ contribs) 07:26, 5 May 2010 (EDT)
Does this work in 64 DS? Arceus79 17:27, 24 March 2012 (EDT)
I know this is an old comment, but I did this on SM64DS. It works just like SM64. Also, I noticed some butterflies that don't give 1-Ups or bombs, but don't go away. While the bombs look like Keronpa Balls in SM64, they may not be Keronpa Balls. I say this because of they keep their appearance in the remake, but Keronpa Balls become more like Flame Chomps. And it isn't a simple matter of just either the butterfly turning into a 1-Up or bomb. See for a better idea. Yoshissm-animated walk.gif Yoshi the SSM (talk) 00:11, 27 October 2018 (EDT)
It's worth noting that their "chase and explode" behavior is similar to the fire-less behavior of Fire/Flame Chomps, which at the time only had faces when breathing. I personally have taken to calling the changed butterfly "Keronpa Krazy." :P Doc von Schmeltwick (talk) 00:54, 27 October 2018 (EDT)