1911] on the Scents of Butterflies. 75 



We conclude, then, that the sceiit-producing function 18 essentially 

 similar in the two kinds of smaller common white. But it is to be 

 observed that the endowments of the two in this respect, though 

 similar, are not identical. The scent in the Green-veined White 

 {Ganon's napi) is, so far as my experience goes, always present and 

 easily recognisable, this being the reason why I chose it for first 

 mention. But with the common Garden White {Ganoris rapae), the 

 case is different. You will probably find some male specimens with 

 no appreciable scent at all : others with the scent so faintly developed 

 that you may be doubtful about its presence ; in none, probably, 

 will the scent be nearly so strong as in the case of the Green-veined 

 AVhite that we began with. Moreover, the character of tlie perfume 

 differs. It has been not inaptly compared to sweetbriar, and it is at 

 all events quite distinct from that of its near relation Ganoris napi. 

 Extending our observations to the Large Cabbage White {Ganoris bras- 

 sicae), we find a plentiful supply of plume-scales of quite a different 

 aspect, these being very much longer, tapering gradually from base to 

 apex, and showing none of the elegant heart-shaped outline that we saw- 

 in the other two species. The regularly disposed fringe or plume of the 

 smaller whites is here also replaced by a kind of untidy bundle. These 

 scales, again, are present only in the male, and only on the upper sur- 

 face of fore and hind wing. What alwut the scent ? It cannot be 

 said to be entirely non-existent, but it is certainly the case that 

 anyone of average olfactory powers may examine many male specimens 

 of the large white without being able to detect any characteristic 

 odour whatever. In some individuals, however, it is unquestionably 

 present, though it is, as a rule, only to be appreciated with difficulty. 

 But when detected it is like a faint whiff of violet powder, or, as has 

 been happily suggested by Dr. Longstaff, orris-root. 



There is in Africa a well-marked " genus," or group of white butter- 

 flies, which goes by the name of Mylotltris. The members of this 

 group are in many respects much like the common whites of our own 

 country ; they are, however, as a rule somewhat brighter in appear- 

 ance, many of them having a touch of vermilion, orange, or some 

 shade of yellow at the base of the wings close to the body. This is 

 more frequent on the under surface, but in many cases it is seen on 

 the upper side as well. The genus also differs from our common 

 whites in usually possessing a distinct marginal row of dark spots. 

 The figures shown on the screen, which were photographed in colour 

 from nature, were prepared for another purpose ■; they give, however, 

 a good idea of the general features of the group. 



Now all the species of Mylothris which I have had the opportunity 

 of examining during life possess a strong and fragrant odour, which is 

 developed under just the same conditions as in the butterflies we have 

 already discussed. That is to say, it belongs to the male alone, and in 

 that sex is confined to the upper surface of the forewings. 



The scent of Mylotkris agathina, which is abundant in many parts 



