246 ANIMAL COLORATION. 



The Occasional Limitation of Mimicry to the Female Insect. 



When the two sexes differ in butterflies, the female appears, 

 according to Dr. Scudder, to diverge more from the typical 

 coloration of the genus or family than the male. This opinion, 

 it should be remarked, is not universally shared; more generally, 

 it is held that the male is the most specialised sex. However, 

 it may not be so in butterflies. 



Among the " Blues," for instance, the normal coloration is, 

 as their popular name denotes, blue ; in some of the species 

 both sexes are blue and closely similar; where there is a 

 divergence, it is the female which differs; the females of many 

 species are brown. This is not the place to discuss how far 

 these differences are due to the greater need for protection by 

 the female; the fact remains that among the butterflies of 

 North America, treated of by Dr. Scudder in his great work 

 upon this group, only one butterfly which is sexually dimorphic 

 has a male which departs from the usual coloration of the 

 family to which it belongs. This butterfly is Ci/aniris pseud- 

 argiolus, a member of the very family which has just been 

 referred to — the " Blues." In this species it is the male, and 

 not the female, which is somewhat dusky in its hues. If the 

 organisation of the female is really more plastic than that 

 of the male, we can understand how in cases of mimicry it 

 is, not nnfrequently, the female only which resembles some 

 other distasteful butterfly ; instances of this havv' been already 

 mentioned (on p. 169). It is quite easy, that is to say, to 

 understand this from one point of view — but from one only. 

 Why are not the males also modified ? They may not require 

 protection quite so much as the females ; but it is obvious 

 that they have their importance in the continuance of the race. 

 The question of heredity may perhaps be set aside ; but even 



