Large Tortoiseshell (Nymphalis polychloros)
Although I have seen polychloros on the continent, including its larval webs, many seasons have passed since I have seen this beautiful butterfly in Britain - and then only a single specimen.
In Victorian times N. polychloros was considered widespread and common in woodland in southern England. However, this stunning insect has subsequently suffered a severe decline to a point of extreme scarcity. N. polychloros, whose numbers were always known to fluctuate, is generally believed to be extinct in the British Isles, with any sightings considered to be migrants from the continent or accidental or deliberate releases of captive-bred stock. Several causes of its decline have been suggested - including climate change, parasitism, and the effects of Dutch elm disease on one of its primary larval foodplants, Ulmus spp. The hope, of course, is that this butterfly is able to once again colonise our islands, and some hope revolves around the few limited sightings from the Isle of Wight each season. Although previously found in many parts of England, Wales and Scotland, the greatest concentrations were in the midlands, south and east of England. This species has not been recorded from Ireland. Recent sightings have come from the south coast, in particular from South Devon, South Hampshire, the Isle of Wight and West Sussex.
I won't hold my breath but fingers crossed …