lOO The Hunting IVasps 



ditions of the nymphs and served me as a 

 standard of comparison, while the others, hung 

 against a white wall, received a strong diffused 

 Hght throughout the day. Under these dia- 

 metrically opposed conditions, the evolution of 

 the colours remained absolutely uniform in both 

 cases, or, if there were some slight discrepancies, 

 these were to the disadvantage of the pupae 

 exposed to the light. It is, therefore, exactly 

 the reverse of what happens in the case of 

 plants : light does not affect the colouring of 

 insects, does not even accelerate the process ; 

 and this must be so, because, in the species 

 which are the most brilliant in colouring, the 

 Buprestes and Ground-beetles, for instance, the 

 wondrous hues which one would imagine to be 

 stolen from a sunbeam are really elaborated 

 in the dusky bowels of the earth or deep down 

 in the decaying trunk of some venerable tree. 



The first outlines of colour show on the eyes, 

 whose faceted cornea changes successively from 

 white to fawn, next to slate-grey, lastly to 

 black. The simple eyes at the top of the fore- 

 head, the ocelh, share in this colouring, in their 

 turn, before the rest of the body has yet lost 

 any of its neutral, white tint. It should be 

 remarked that this early development of the 

 most delicate organ, the eye, is general in all 

 animals. Later, a smoky line appears on the 



