63 



Remarks on Pieris Napi and Allied Forms. 



By J. Jenner Weir, F.L.S., F.E.S., etc. 

 Abstract of paper read February nth, 1892. 



The object of the Exhibition was rather to show the effect of en- 

 vironment and season of emergence on the intensity of coloration, 

 both on the upper and under side of the wings. In the ordinary 

 form of Pieris napi the male is usually almost pure white above, 

 with faint greyish tips to the wings ; the female has the wings more 

 suffused with greyish scales, and with three well-developed greyish 

 spots on the upper, and one at the costa of the lower wings ; under- 

 neath, both sexes have the nervures and nervules with dark scales 

 running densely along their course, the upper wings being white, with 

 yellow tips, and the lower wings yellow. In the form which appears 

 during the summer, the male is white, with well-marked greyish tips 

 to the upper wings, and a black spot between the second and third 

 median nervules ; the female has the markings of a deeper black, 

 and an additional mark between the sub-median nervure and the 

 lower median nervule; the underside of the lower wings in both 

 sexes have very much less of the dusky scales on the nervures ; the 

 ground colour of the wings in the male are lemon-coloured, and that 

 of the female yellow. The differences between the colour of the two 

 emergences may be summed up thus : the male of the spring form is 

 lighter above and darker underneath than the same sex of the summer 

 emergence, and the female of the spring form is less black above, 

 though more dusky, and much darker below than the female of the 

 summer emergence. 



Some specimens from Cavan, which had been taken in August, 

 also showed deep black markings, and the nervures of the female, 

 even on the upper side, were black ; the under sides were darker 

 than usual in English examples. At the same time that these were 

 taken a bryonice. was found with them, also exhibited ; this was the 

 more remarkable because that variety is more nearly like the spring 

 than the autumnal emergence of the species. As further illustrating 

 the subject, a female from St. Petersburg of the spring emergence 

 was shown, which had the whole of the nervures of both wings above 

 conspicuously marked with dusky scales, and a female from the same 

 place, of the summer emergence, which was almost as free from 

 dusky scales on the under side of the hind wings as a Pieris rapce. 



Specimens as large as Pieris brassicce were shown, of the variety 

 or sub-species P. meleie, from Western China, taken at a height of 

 1,700 feet, in July; the males, except in size, differed but Httle from 

 the ordinary form , but the female had the nervures deeply edged 

 with dusky scales, and the whole of the wings suffused with grey, 

 and an additional spot between the second and third median nervules 

 on the upper side of the lower wings. Specimens of the closely 

 allied Pieris oleracea, from Moose Factory, had the males nearly 



