PEOTECTIVE MIMICRY 239 



world that the females are far more liable to 

 assume this method of defence than the males. Thus 

 Mr. Wallace found that the eastern Morphidcs and 

 the special group of Swallow-tails were only mimicked 

 by the females of other Swallow-tails ; and similar 

 facts have been observed in America. 



Mr. Wallace, in his paper on the Malayan Swallow- 

 tails, explains the commoner mimetic resemblances of 

 females, because ' their slower flight, when laden with 

 eggs, and their exposure to attack while in the act 

 of depositing their eggs upon the leaves, render it 

 especially advantageous for them to have some addi- 

 tional protection.' 



Mr. Belt adopts the same explanation, and also 

 makes the very ingenious suggestion that, when the 

 males have not been similarly modified, it is because 

 of the preference of the more conservative sex for con- 

 sorts which retain the ancestral colour of the group 

 to which they belong. He points out that the males 

 of many of the mimetic * Whites ' (Pierida) ' have the 

 upper half of the lower wing of a pure white, whilst 

 all the rest of the wings is barred and spotted with 

 black, red, and yellow, like the species they mimic. 

 The females have not this white patch, and the males 

 usually conceal it by covering it with the upper wing, 

 so that I cannot imagine its being of any other use 

 to them excepting as an attraction in courtship, to 

 exhibit to the females, and thus gratify a deep-seated 

 preference for the normal colour of the order to which ' 



