These images show caterpillars of the Peacock butterfly seen in SW London on 20th June. Their communal webs were covering the growing tips of the nettles on which they were feeding, and as can be seen, they migrate to fresh plants as each is stripped bare. The feeding damage, swathes of web, and the black, spiny caterpillars were very conspicuous and in several places in a big patch of nettles which looked black from a distance then as we moved closer were alive with these caterpillars. Eventually these caterpillars will disperse to pupate suspended from vegetation. The Peacock is widespread and common in the south of Britain and Ireland, but less frequent to the north and at higher altitudes.