IIISrORY OF ZOOLOGY. 



49 



clumsy and yet unmolested liy birds, because they contain bad- 

 tasting fat bodies. Another species of butterfly accomimnies them 

 (Pieridas), which does not taste Ijad, and yet are not eaten, because 

 in flight, in cut, and marking of the wings they imitate the 

 HdiconicB so closely that even a systematist might easily be 

 confused (fig. 13). In a similar way bees and wasjjs, feared on 

 account of their sting, are imitated by other insects. In Borneo 

 there is a large black wasp, whose wings have a broad white spot 



Fig. 14. — a, Mygnimia avicxiluf^, a wasp imitated by a beetle ; h, Colohorhntuhus fa.-^rid- 

 tipcnnU. (After Wallaee.) I nat. size. 



near the tip {Mi/gnimia aviculus). Its imitator is a heteromerous 

 beetle (C'oloborhombus fasciatipeiniis), which, contrary to the li;ibit 

 of beetles, keeps its hinder wings extended, showing the white sjjot 

 at their tips, while the wing-covers have become small oval scales 

 (fig. U). 



Sexual Selection is a special phase of natural selection, chiefly 

 observed in birds and hoofed animals. For the fulfilment of his 

 sexual instincts the male seeks to drive his competitors from the 

 field, either in battle or by impressing the female by his special 



