272 
DARWINISM 
CHAP. 
A hundred other cases might he quoted in which the 
female is either more obscurely coloured than the male, or 
gains protection by imitating some inedible species ; and any 
one who has watched these female insects flying slowly 
along in search of the plants on which to deposit their 
eggs, will understand how important it must be to them 
not to attract the attention of insect-eating birds by too 
conspicuous colours. The number of birds which capture 
insects on the wing is much greater in tropical regions 
than in Europe; and this is perhaps the reason why many 
of our showy species are alike, or almost alike, in both 
sexes, Avhile they are protectively coloured on the under side 
which is exposed to view when they are at rest. Such are 
our peacock, tortoise-shell, and red admiral butterflies; while 
in the tropics we more commonly find that the females are 
less conspicuous on the upper surface even when protectively 
coloured beneath. 
We may here remark, that the cases already cpioted prove 
clearly that either male or female may be modified in colour 
apart from the opposite sex. In Pieris pyrrha and its allies 
the male retains the usual type of coloration of the whole 
genus, while the female has acquired a distinct and peculiar 
style of colouring. In Adolias dirtea, on the other hand, 
the female appears to retain something like the primitive 
colour and markings of the two sexes, modified perhaps for 
more perfect protection ; while the male has acquired more and 
more intense and brilliant colours, only showing his original 
markings by the few small yellow spots that remain near the 
base of the wings. In the more gaily coloured Pieridse, of 
which our orange-tip butterfly may be taken as a type, we see in 
the female the plain ancestral colours of the group, while the 
male has acquired the brilliant orange tip to its wings, prob¬ 
ably as a recognition mark. 
In those species in which the under surface is protectively 
coloured, Ave often find the upper surface alike in both sexes, 
the tint of colour being usually more intense in the male. But 
in some cases this leads to the female being more conspicuous, 
as in some of the Lycsenidje, Avhere the female is bright blue 
and the male of a blue so much deeper and soberer in tint as 
to appear the less brilliantly coloured of the two. 
