196 ANIMAL COLOEATION. 



sought after by birds, should come to resemble an uneatable 

 butterfly, it might often be mistaken for it and so escape 

 destruction. Natural selection, it is thought, has acted upon 

 the originally slight variations of certain Pieridte, and produced 

 the often wonderfully close similitude to the Heliconida3 which 

 we now see. 



Mimicry often found only in Females. 



There are plenty of examples of this phenomenon, which is 

 occasionally confined to the female sex. It is more important 

 for the continuance of the species that the female insect 

 should be preserved ; and, just as among birds we often 

 meet (see p. 258) with examples of jjrotectively coloured 

 females and brightly coloured males, there are instances among 

 butterflies where the female alone shows a protective mimicry. 

 Mr. Trimen has described and figured an African " Swallow- 

 Tail " in which the female is entirely without the " tails " 

 which are usually so conspicuous a feature of the group. 

 There are three distinct varieties of the female insect, each 

 of which mimics a particular form of Danais occurring in the 

 same district. Danais is said to be an unpalatable butterfly, 

 and avoided on that account. 



Are the Danaidse strongly scented, like the Heliconidsel 



It is not reasonable to lay much stress upon the fact of 

 insects possessing qualities which are disagreeabh> to our- 

 selves ; for it by no means follows that these same ijualities 

 affect the enemies of the insects ; indeed, there is experimental 

 evidence that the reverse is the case. With respect to the 

 Danaida^, Acrjeidfe, and Heliconidie, — the typical families 

 which are models for mimicry, — Mr. Poulton says that 



u 



peculiar and frequently unpleasant smell has been noticed 1 



IV 



