38 THE ENTOMOLOGIST. 



Mr. G. V, Hudson, the well-known Wellington entomologist, 

 whom I requested to examine the group, has favoured me with a 

 note regarding them ; he considers them " most interesting and 

 instructive," and states that he has specimens from the Nelson 

 province " differing altogether " from them. As Nelson is west 

 of the Alps in the South Island, the fact proves that the variation 

 of the species is nowhere local, but general over the whole extent 

 of the South Island. For many years I have collected in different 

 parts of Canterbury, south of the Rakaia river, from the sea- 

 shore to several thousand feet up the grassy slopes of the Alps ; 

 and for three seasons I collected in North Otago, a district 

 which has been under cultivation for over a quarter of a century. 

 After examining the specimens in the Dunedin Museum, cap- 

 tured in other localities in Otago, I think that no locality can 

 be given as producing more varied forms, but that the remark- 

 able variation of the species is unquestionably general over the 

 whole area of the South Island. 



As the great question of variation is of vital importance in 

 fully elucidating the science of entomology, it seems to me 

 imperative that entomologists should record the slightest varia- 

 tion in any species when first observed, as in some instances it 

 has now assumed such complexity as to be almost impossible to 

 trace its origin. A thorough knowledge of climatology in all its 

 bearings on the variation of insects is also indispensable to every 

 entomologist. There can be no question that many species of 

 Lepidoptera are greatly influenced in all stages by changes of 

 temperature or by the seasons ; and from notes on the variation 

 of this butterfly in relation to the seasons, made during many 

 years, I am in a position to show that the species exhibits greater 

 variation in some years than others. The winter (or wet season 

 in New Zealand) of 1881 was exceptionally dry and mild during 

 the summer, which was even and hot; the butterflies emerged in 

 prodigious numbers, but all the individuals I examined showed 

 less aberration in that year, including the early months of 1882, 

 than any season I can give, before or since. The following winter 

 was much colder, and was succeeded by a fine even summer ; but 

 the butterflies were nowhere so plentiful, and many of them, 

 especially the males, were more variably marked than those of the 

 preceding summer. Then followed the wettest winter, and 

 equally wet and coldest summer, on record in New Zealand ; 

 every day of bright sunshine produced the emergence of some, 

 and fresh individuals continued to appear until much later in the 

 season than usual. In the same year (the early months of 1884) 

 I collected the most variable forms of both sexes I had hitherto 

 obtained. The close of the year and the first six months of 

 1885 were the hottest on record ; and although the butterflies 

 were plentiful, the greater number I netted were not so variable 



