80 



On certain Butterfly Scales characteristic of Sex. By 

 T. W. AVoNFOR, Hon. Sec. 



(Read before the Members of the Brighton and Sussex Natural History 

 Society, Nov. IS 67.) 



Nearly every one who has worked with the microscope 

 and turned his attention to the scales of insects (especially 

 the Butterfly tribe) has perhaps been struck with the great 

 variety of form to be found not only in difierent butterflies, 

 but on the under and upper side of the wings of the same 

 insect. If, too, an attempt has been made to find in the 

 " whites " or " blues " the scales described in all works on 

 the Microscope, as found on certain members of each group, 

 he has undoubtedly met with disappointment, especially if 

 he has looked where our standard works tell us they are to 

 be found. Thus, in the case of the azure blue {Polyoni- 

 matus argiolus), we meet with instructions tending to mis- 

 lead; thus in the ' Micrographic Dictionary,' under " Poly- 

 ommatus," p. 564, we read — " The scales upon the under 

 surface of the wings of P. argiolus and P. argus have been 

 proposed as test objects. They are of two kinds — one re- 

 sembling in structure the ordinary scales of insects, the other 

 of a battledore form." Again, under the head of " Pontia," 

 ji. 571 : — " The form and structure of certain scales existing 

 upon the under side of the male is curious." Now, any in- 

 quirer looking, in either case, in the situations named, will 

 undoubtedly not find them, for the simple reason that these 

 particular scales are never found on the under side. 



It was in endeavouring to work out, in 1864, these and a 

 kindred scale that I hit upon certain facts, which perhaps may 

 have been discovered before ; but as I have not been able to 

 find any record of them, I thought the subject sufficiently inte- 

 resting to bring before the microscopic world. One fact has 

 reference to the position of the battledore scales ; the other 

 tends to the belief that they, and certain other forms to be 

 described, are, in the three families of the Polyommatus, 

 Pontia (or Pieris), and Hipparchia, characteristic marks of 

 sex — at least I have j^roved such to be the case, as far as I 

 have been able to obtain specimens for observation. In the 

 " blues " proper there is a marked dissimilarity in the colour 

 of the sexes ; for, while the males are of various shades of 

 blue, answering to the names azure, mazarine, &c., the 

 females are of a brownish hue, spotted or dashed Avith bluish 

 scales. Any person seeing them together for the first time 



