When it comes to caterpillars, I know that I am meant to hate the Cabbage White (Pieris rapae, if you will), as it does so much damage, however I heard recently on the news that some species of butterfly are becoming rare and I don't want to be part of a mass extinction movement. I have thought about finding info on caterpillars, though I haven't really tried that hard, I mean I haven't 'Googled' it, looked for a book or anything, but last night on the BBC Gardening message board there was the answer, just waiting for me.
Kindly, a certain 'David K' had passed on this website, which helps to identify caterpillars and has plates which shows them and the plants they are usually found on, good info to have I thought. So I too shall share.....
By actually taking the time, I have now found (by myself) The Butterfly Conservation Website
so by checking what caterpillars we have and looking them up we can save the rare ones. Thus allowing us to get up on that high moral seat and feel smug. Lovely.