170 



ANIMAL COLORATION. 



teria. However, there are other Papilionid larvae which 

 are undoubtedly conspicuous. The North American Laertias 

 philenor, the " Blue Swallow-tail," is ; and it has the same 

 osmateria as the European Papilio machaon. 



These facts are hard to reconcile with the theory of warning 

 colours. Presumably, the bright colours of the larva of 

 Laertias philenor are an advertisement of the osmateria ; and 

 yet these same weapons of offence are not advertised in 



Fig. IS. Swallowtail Butterfly and Larva. 



Papilio machaon and in other species with a defensive or 

 at least a non-conspicuous coloration. 



Mr. Scudder thinks that possibly the explanation is that 

 the larva of the American Swallow-tail conceals itself under 

 leaves, and is therefore less readily found. But this explana- 

 tion is not consistent with the theory of warning colours : the 

 very essence of the theory is that brightly-coloured larvae 

 display themselves in the most open way. 



Another great difficulty in the way of accepting the theory 

 of warning colours is the actual change which must take 



