The blackleg tortoiseshell or large tortoiseshell (Nymphalis polychloros) is a butterfly of the family Nymphalidae.
Tree sap and damaged ripe fruits are particularly suitable sources of food for this butterfly. The females lay their pale green eggs in a continuous band around the upper twigs of elm, sallow, pear and prunes trees.
It is found in Europe, northern Africa, and western Asia. It is an extreme rarity in Britain, although it used to be widespread throughout England and Wales.
It looks very like the small tortoiseshell (Nymphalis urticae), here left, with some differences in numbers and colors of the spots: