「蝶よ花よ」is highly idiomatic. My dictionary (広辞苑 ) says 蝶よ花よ is「子をいつくしみ愛する様を言う語」. See also: http://kotobank.jp/word/%E8%9D%B6%E3%82%88%E8%8A%B1%E3%82%88 It'd be like...「女の子が『蝶よ花よ』と（両親に）言われながら育てられる。」(蝶よ花よ is said by the parents to the daughter... Probably it's like "Oh look at the butterfly, look at the flower, aren't they lovely, you're lovely too / All you have to see is beautiful things on earth, you wouldn't have to see anything ugly, wouldn't have to face difficulties"...?? ) So the phrase is used to describe how a daughter's parents bring her up with affection and care, like a princess. They love, cherish or even spoil her. The よ in 蝶よ花よ is a particle. (I read on the net that the phrase used to be 蝶や花や or 花や蝶や... and also that it evolved into ちやほや...)

hello we never use this form when we speak... so i don't think this sentence does make sence. but when i listen to the song, it gives me an impression that it says, ''live saying oh flower oh butterfly '' so after all, this sentence want to say that ''taking nature for a friend'' or something like that i think.