The Larva and the Nymph 



the best part of the wrapper, is thrown off by 

 means of alternate contractions and expan- 

 sions of the abdomen. By this mechanical 

 process it is slowly forced backwards, where 

 it ends by forming a little pellet that for some 

 time remains fastened to the insect by the 

 tracheal gills. The Sphex then once more 

 becomes motionless; and the operation is over. 

 However, the head, antennae and legs are still 

 more or less veiled. It is evident that the 

 legs in particular cannot be freed all in one 

 piece, because of the numerous excrescences 

 or spines with which they are armed. These 

 different shreds of skin dry up on the insect 

 and are removed afterwards by rubbing the 

 legs. It is not until the Sphex has acquired 

 her full vigour that she finishes her moulting 

 by brushing, smoothing and combing her 

 whole body with her tarsi. 



The way in which the wings come out of 

 their sheaths is the most remarkable part of 

 the sloughing. In their incomplete stump 

 stage, they are folded lengthwise and are very 

 much compressed. It is easy to extract them 

 from their cases a little while before the 

 normal date of their appearance; but then 

 they remain permanently contracted and do 

 not fill out. On the other hand, when once 

 iii 



