THE COLOURS OF THE LEPIDOPTERA i6i 



Pigments and Mimicry 



Mr. Hopkins notes in relation to the question 

 of mimicry that the pigments of the Heliconidae 

 are not the same as those of the Pieridse, for though 

 soluble in water they do not give the murexide 

 reaction. He regards this as evidence against the 

 views of those who hold that the resemblances of 

 mimicry may be due to relationship between the 

 forms. We do not propose to discuss the question 

 of mimicry here, but may just note that mimicked 

 species usually display what are known as " warning 

 colours," which apparently, in butterflies at least, are 

 always pigmental colours, or the simple types of 

 optical colour like white and black. Now as there 

 are in butterflies, apart from structural colours, only 

 about three pigments to choose from (yellow, red, 

 brown, and rarely green), the range, if we may 

 so speak, is somewhat limited. Apart from the 

 question whether the presence of the yellow and 

 red pigments in considerable amount is not a sign 

 of little specialisation, the frequent absence of 

 structural colour from these " warning " forms is at 

 least probably such a sign. Instead therefore of 

 supposing that the Heliconidae have, in Mr. Wallace's 

 words, " acquired lazy habits " and a slow flight 

 because they are uneatable, and the Pieridse because 

 they resemble the Heliconidae, may we not rather 

 suppose that the slow flight and " warning " colours 

 in both cases are due to the same cause, the 

 relatively low organisation which renders pigmenta- 

 tion by waste products possible, which makes brilliant 



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