none Examination of the available national average weather records from the earliest dates possible for temperature and rainfall on a monthly, seasonal, annual and twenty-year-running-average basis since the 17th century shows that the only significant relationship with the fluctuations of Aporia crataegi L. is that of September rainfall. There seems little doubt that the cause of the disappearance was multifactorial - the unique coincidence of several adverse influences. There is considerable circumstantial evidence to suggest that the butterfly was severely affected by a disease in historical times. There are inferential indications that a fungal epizootic was the most probable disease encountered, although the possibility of a virus disease cannot be eliminated. With disease being the primary culprit, it is likely that avian predation also contributed heavily to the decline, with other of the more usual deleterious factors following. Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Pollution; Land and freshwater zones; Palaearctic region; Europe Aporia crataegi (Pieridae); Hymenopteran parasites; Apanteles glomeratus; Chemical pollution; Pesticides, not regarded as primary cause of extinction in Britain; United Kingdom; Extinction, causal factors, review & conclusions Apanteles glomeratus (Braconidae); Lepidopteran hosts; Aporia crataegi; Not regarded as primary cause of extinction of host in Britain; United Kingdom; Not regarded as primary cause of extinction of lepidopteran host