The Northern Brown Argus, Aricia artaxerxes, is one of the few butterflies in Britain restricted to northern England and Scotland. It also has the distinction of being the last butterfly to be added to the British list of resident species. Until the painstaking breeding experiments of Jarvis in the 1960s (Jarvis 1962, 1966), the butterfly was described as a sub-species of the Brown Argus, Aricia agestis.