Fairy? Or Butterfly?

Now I know this is quite a strange topic but my friend just asked me, what would I like on the end of the pair of wings she just drew, a fairy? Or a butterfly? And that got me thinking. How did fairies end up being introduced with butterfly wings? I'm pretty sure some authors of fairy tales like Cinderella had a reason to make fairies appear half butterfly. Maybe it was to make them appeal to the younger audience? Or maybe it was just to make them look pretty and magical. Well whatever the reason it is quite strange to portray fairies and fairy tales like this:



When they originally looked like this:



Which is a Sidhe. Pronounced 'she'.

See? MASSIVE DIFFERENCES!
But really...maybe fairies got portrayed like this because it's just their view on what they should look like? Or maybe I should just Google it instead....oh the vast knowledge of Google. What would we do without it?
Anyway, I'm off to look up 'Fairies' on Google. This will be a dangerous adventure. I will come across many evil monsters such as the laughing females and the curious friends. Meh. Well I shall stop boring you now with my ranting. Farewell fair strangers.