XX 



INSECTA: NEUROPTERA 



301 



neath. Next the skin splits down the mid-line of the thorax, 

 and the body within swells up, causing the split to extend 

 forwards right to the eyes, 

 and down each side close to 

 them. In this way the head 

 and thorax, with the still 

 minute wings, are freed, and 

 next the legs are drawn out of 

 the old skin, the thorax and 

 head being strongly arched 

 outwards to accomplish this, 

 and, at the same time, to cast 

 off the four chief tracheae, 

 which are shed with the ex- 

 ternal skin. The tracheae 

 remain behind, as two white 

 threads attached on each side 

 of the thorax of the larval 

 skin (Fig. 222, t). After this, 

 the insect throws its head and 

 thorax right back until they 

 almost touch the abdomen 

 (Fig. 222), and in this curious 

 position supported only by 

 the tip of the abdomen, which 

 remains inside the old skin it . rests sometimes as long 

 as half an hour, waiting doubtless for its newly exposed 

 legs and claws to harden, and for its body to gain strength 

 for the sudden jerk forwards, with which finally the body is 

 brought back into a more normal position, the claws grasping 

 firmly the sides of the discarded skin (Fig. 223). Then it 

 proceeds to withdraw the end of its abdomen, pulling it 

 carefully out of the original split in the thoracic wall, and 

 having, therefore, to arch its whole body strongly to free it 

 (Fig. 223), though as soon as it is free it is extended, arid 

 curves up away from the original skin (Fig. 224). The 

 imago now usually leaves its old skin, climbing up a few 

 inches above it (Fig. 225). 



There is, however, considerable further development to 

 take place before the mature adult form is attained. The 

 wings are still small and rudimentary, the vivid adult colour- 



Fro. 222. Early stage in the last 

 moult of the Nymph of A esclina. 



larval or nymph skin, l.s.; w, crumpled- 

 up wings of imago ; t, tracheal threads 

 of nymph withdrawn from body of 

 imago. 



