Is it being studied?
"Evolution" is not about unthinkingly giving the same answer for everything like...oh, I don't know..."God did it".
Or I don't know "evolution did it".
No-one says that.
That's the point.
Evolutionary theory doesn't rely on simple binary statements like religion.
It's a study of processes.
Your butterfly example could, for example, be a result of climate change.
Maybe the butterflies used to breed in a place that was very near their main source of food but, as climate has changed over the years the food source has moved and they've moved with it but kept returning to the same place to breed.
The distance has increased slowly over the years and they've just continued to fly the extra few metres each time.
Maybe.