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Show 142 DR. A. G. BUTLER ON SEASONAL [June 7, 2. On Seasonal Phases in Butterflies. B y A . G. B u t l e r , Ph.D., F.L .S ., F.Z .S ., &c. [Received May 10, 1904.] The fact that Butterflies emerged from the pupa in markedly different forms at different times of the year was made evident many years since by the labours of W. H. Edwards in the United States, by Mansel Weale in South Africa, and by Doherty and de Niceville in India; but this fact was misunderstood, and therefore not fully accepted by many workers for years afterwards, whilst not a few are sceptical as to its truth at the present day. One of the chief reasons for this scepticism is based upon the unquestionable truth that the dry-season type of a species not unfrequently emerges in the wet season and vice versa. That I was myself rendered sceptical for years on this ground will be seen by referring to some of my earlier papers in which the question of seasonal forms had to be considered. In a paper published in 1884 (P. Z. S. pp. 478-501) I recorded the remarkable fact that, at Aden, Limnas chrysippus, Hypolimnas misippus, and Catopsilia florella produced all their varietal phases simultaneously, and that Teracolus " nouna " = saxeus (which actually is the T. evagore of Klug) occurred in March, April, and May, whilst T. yerburii was also obtained commonly in April and May; but I did not then fully appreciate the fact that all these were instances of the simultaneous emergence of phases characteristic of seasons and climates, and that they represented the probable condition of all very variable types before seasonal or climatic changes had begun to act upon them. As with protective mimicry, the more enthusiastic exponents of which have frequently erred in supposing that because this was of use against one enemy, it must necessarily be against all; so has it been with those who desired to believe in, but failed to comprehend, seasonal variation. That I misunderstood it myself in 1886 is clear from the remarks which I made in a paper upon Lepidoptera from Western India (P. Z. S. p. 399) respecting the broods of Belenois mesentina: in 1888 I was no wiser, as my remarks emphasising the importance of dates of capture in the case of certain species of Teracolus clearly show (Ann. & Mag. Nat. Hist. ser. 6, vol. i. p. 201). In 1895 (P. Z. S. p. 727) I hinted at the possibility of Hypan-artia schceneia and II. hippomene being seasonal forms of the same species, and in 1896 (P. Z. S. p. 112) I considered this probable ; yet later in that year (P. Z. S. p. 285) I concluded that this was an error, because both were captured on the same mountain upon two successive days. At this date, therefore, it is quite evident that I considered it impossible for wet and dry phases of any species to occur simultaneously. Indeed, it was only after reflecting upon the probable identity of T. yerburii with the supposed T. nouna (P. Z. S. 1896, p. 247) that I began |
