NATURAL SELECTION 



butterfly, Papilio paradoxa. I have since named this 

 interesting species Diadema anomala (see the Transactions of 

 the Entomological Society, 1869, p. 285). In this case, and 

 in that of Diadema misippus, there is no difference in the 

 habits of the two sexes, which fly in similar localities ; so that 

 the influence of " external conditions " cannot be invoked 

 here as it has been in the case of the South American Pieris 

 pyrrha and allies, where the white males frequent open 

 sunny places, while the Heliconia-like females haunt the 

 shades of the forest. 



We may impute to the same general cause (the greater 

 need of protection for the female, owing to her weaker flight, 

 greater exposure to attack, and supreme importance) the 

 fact of the colours of female insects being so very generally 

 duller and less conspicuous than those of the other sex. And 

 that it is chiefly due to this cause rather than to what Mr. 

 Darwin terms " sexual selection " appears to be shown by the 

 otherwise inexplicable fact, that in the groups which have a 

 protection of any kind independent of concealment, sexual 

 differences of colour are either quite wanting or slightly 

 developed. The Heliconidae and Danaidae, protected by a 

 disagreeable flavour, have the females as bright and con- 

 spicuous as the males, and very rarely differing at all from 

 them. The stinging Hymenoptera have the two sexes equally 

 well coloured. The Carabidse, the Coccinellidae, Chrysomelidse, 

 and the Telephori have both sexes equally conspicuous, and 

 seldom differing in colours. The brilliant Curculios, which 

 are protected by their hardness, are brilliant in both sexes. 

 Lastly, the glittering Cetoniadae and Buprestidae, which seem 

 to be protected by their hard and polished coats, their rapid 

 motions and peculiar habits, present few sexual differences 

 of colour, while sexual selection has often manifested itself 

 by structural differences, such as horns, spines, or other 

 processes. 



Cause of the dull Colours of Female Birds 



The same law manifests itself in Birds. The female while 

 sitting on her eggs requires protection by concealment to a 

 much greater extent than the male ; and we accordingly find 

 that in a large majority of the cases in which the male birds 



