112 INSECT LIFE 



VIII 



orange-red, and the tip black. The h'very would 

 then be complete, but that the tarsi and mouth- 

 pieces are transparent red and the stumps of wings 

 ashy black. Four - and - twenty hours later the 

 chrysalis will burst its bonds. It only takes six 

 or seven days to acquire its permanent tints ; the 

 eyes have done so a fortnight before the rest of 

 the body. From this sketch the law of chromatic 

 evolution is easily apprehended. We see that, 

 omitting the eyes and ocelli, whose early perfection 

 recalls what takes place in the higher animals, the 

 starting - point of coloration is a central one, the 

 mesothorax, whence it invades progressively by 

 centrifugal progression — first the rest of the thorax, 

 then the head and abdomen, and finally the various 

 appendages, antennae, and feet. The tarsi and 

 mouthpieces take colour later still, and the wings 

 only on coming out of their cases. 



Now we have the Sphex in full costume, but she 

 still has to free herself from the chrysalis case. 

 This is a very fine wrap, enfolding every smallest 

 detail of structure, and hardly veiling the shape 

 and colours of the perfect insect. As prelude to 

 the last act of metamorphosis, the Sphex, rousing 

 suddenly from her torpor, begins to shake herself 

 violently, as if to call life into her long-benumbed 

 limbs. The abdomen is alternately lengthened and 

 contracted, the feet are suddenly spread, then bent, 

 then spread again, and their various joints are 

 stiffened with effort. The creature, curved back- 

 wards on its head and the point of the abdomen, 

 with ventral surface upward, distends by vigorous 

 shakes the jointing of its neck and of the petiole 



