Yes. That was of my main concerns actually, losing the butterflies....I'm leaving one big patch of nettles down at the bottom...I've just been out there now and there are lots of hibernating ladybirds in amongst them...hope they're the indigenous variety. We have Budleja and Alysum and other butterfly attracting plants and a huge lavender bed.. I do like to attract wildlife, in whatever form, into the garden.
I think the digging sounds the best bet, if not the easiest! If it weren't for the fact that they're monopolising the raised beds, I'd leave them be.