WARNING COLOURS 191 



The transition from Sexual to Warning Colours 



The two groups nevertheless run into each other, 

 and a beautiful transition is afforded by the insects 

 in which sexually produced colours and patterns are 

 made use of for warning purposes. When this is the 

 case the colours spread on to the parts which are ex- 

 posed during rest, and the flight becomes sluggish, so 

 that they are displayed as completely as possible. 

 These are the insects which are the principal models 

 of mimicry in tropical countries, and Bates's classical 

 paper, in which an intelligible theory of mimicry was 

 first brought forward, deals with the groups which are 

 found in the Amazon valley, and with the forms which 

 resemble them and share the advantages conferred by 

 their well-known and nauseous qualities. The evi- 

 dence for the existence of such qualities is better 

 considered under the next heading, viz. Mimicry. 



Resemblance between such Warning Colours in different 

 species 



The members of each of these groups resemble one 

 another to a marked extent ; far more so than the 

 species of other groups without Warning Colours. 

 Thus the advantage of facilitating the education of 

 enemies is gained by them, although it has arisen in a 

 manner different from that already described in other 

 unpalatable insects (see pp. 184-86). 



