172 COLOUR IN NATURE chap. 



and DiPTERA may be mentioned as exhibiting a 

 striking parallelism of coloration. In various instances 

 (e.g. Volucella, Eristalis, etc.) this has of course been 

 described as protective mimicry on the part of the 

 flies, but it is difficult to look at collections of the 

 two orders side by side without being struck by the 

 similarities of colouring. In both cases the body is 

 frequently covered with hairs which are important 

 factors in coloration, but the hair may be completely 

 absent and the surface may be then brilliantly 

 metallic or black and polished -looking. Among 

 pigmental colours in both cases black, dull brown, 

 and yellow are the commonest. There seem to be 

 no investigations on the pigments in either case. 



Contrast between Coloration of Lepi- 

 doptera and other insects 



In comparing the colours of other insects with 

 those of the Lepidoptera, we have to notice that in 

 the former the occurrence of much beauty or special- 

 isation of colour in the larvae is relatively rare. The 

 larvae not infrequently are of the form popularly 

 known as maggots or grubs, and they are usually 

 colourless or almost so. Similarly, outside the 

 Lepidoptera, it is not very common to find the 

 nutritive and reproductive stages sharply contrasted 

 in large groups, many of the adults being not in- 

 frequently both. Directly associated with this fact, 

 or as the indirect result of the diminished specialisa- 

 tion which makes food-taking possible to the adults, 

 we find that the adults may display that type of 

 coloration which is larval for the Lepidoptera, that is 



