Punctuation

I hate misplaced commas - this one wasn't.

The comma butterfly is one of the beneficiaries of climate change; it has extended its range from Southern England and the Welsh border all the way up to Scotland. Prior to that it had survived a serious challenge when, towards the end of the 19th century, the cultivation of its main larval food plant, hops, started to decline. During the course of the 20th century the comma switched to nettles and recovered.

Here is some truly astounding footage of a comma caterpillar pupating followed by the pupa hatching into a butterfly. Incredible process, incredible photography.