My friend was told when she was a child (and still believes this) that butterflies are called 'butterflies' because they were originally called 'flutterbies' (because, of course, they flutter by) and that people got confused somewhere along the way.
A childhood belief about general

others believed things like this
- I used to believe that butterflies would eat your nose.— Kate G.
- I used to think that butterflies made butter— Christophe R.
- I used to think butterflies were made of butter.Anon
- i used to believe that butterflies are fairies that crossed the rainbow— sillyme
- I believed butterflies taste like butterAnon
- When I was little I was absolutly positive that butter was made by butterflies.— Ruth