ON THE VAEIATION OF ARGYEOPHINGA ANTIPODUM. 39 



or richly marked as in the preceding year. The two succeeding 

 summers produced specimens which were about equal to 1885, as 

 regards their numbers and markings. Last summer, which was 

 preceded by a very wet winter, there was again a greater number 

 of more richly marked and variable forms. 



From the foregoing notes it will be seen that the variation of 

 the species is most predominant in seasons succeeding wet winters. 

 The same applies to Clirysoj^hanus holdenarum. How the seasons 

 operate in producing this effect requires careful investigation, and 

 any satisfactory solution of this interesting and difficult problem 

 can only, I think, be obtained through such recorded obser- 

 vations. [Vide ante, p. 20. — Ed.] 



One cause in New Zealand which affects the numbers and 

 economy of many species of insects is the annual burning of the 

 Tussock lands. They are fired to promote the growth of young 

 grass, for sheep and cattle depasturing on it. I have no doubt 

 that these terrible fires which occur in the early spring months, 

 sometimes lasting for days, and spreading over many miles of 

 open countr3',have long ago extirpated many species of insects and 

 rendered others rare. Indeed, it is surprising that A. antiiJodum 

 holds its own so well, seeing that it is in all stages almost 

 exclusively a Tussock-frequenting species. 



In the early days of the colony the seasons were more equable 

 than now. The winter rains were more periodical, with less 

 frost ; and the summers more even, with fewer chills. The 

 devastating fires, together with cultivation of the land, would 

 soon assert their influence on the climate, and materially affect the 

 economy of Lepidoptera. An abundance, scarcity, or change of 

 food and environment, during the larval stage, is known to 

 produce great variations among certain species ; with A. anti- 

 podiini, the fiiiesi marked and best-developed forms are evolved in 

 humid seasons, and such succeeding wet winters. Tlie abundance 

 of food which obtains, and an unchecked and vigorous growth of 

 the larvffi during sucli seasons, would account for this. I cannot 

 say whether natural selection, in the case of the female, *' plays 

 many parts in perpetuating the variation of the species," as I 

 have only twice observed them in copula ; but in both cases the 

 males were large and richly-marked individuals. Neither am I in 

 a position to say that the tendency to darkening in the colours of 

 the species is, in humid seasons, a case of atavism ; but I 

 incline to such an opinion, as the preceding geological period in 

 New Zealand was iunnensely more humid than the present, a 

 fact wiiich I think favours such a view. 



On some future occasion I hope to add a little more on the 

 subject, and to give the life-history of this peculiar butterfly. 

 East Belt, Ashburton, New Zealand, September 15th, 1888. 



