32 



ELEMENTARY LESSONS ON INSECTS 



for example, is very 

 different from the 

 adult (compare 

 figures 16 and 18). 

 The accompanying 

 figures (see figure 

 12) show the 

 change in progress. 

 In 1 — the nymph 

 has climbed from 

 the water up a 

 post attached its 

 claws firmly, and 

 the adult has lifted 

 its head out through 

 a rent in the back 

 of the old nym- 

 phal skin. In 2 — 

 head, thorax, wings 

 and legs are all 

 out, and the crea- 

 ture is hanging by 

 its still enclosed 

 tail, momentarily resting. In 3 — the adult has righted 

 itself and is standing on the now empty skin, but its wings 

 are not yet fully expanded. This is, indeed, a transformation. 

 It may require half an hour for completion. During this 

 time the callow insect is peculiarly helpless. 



Fig. 13. — The developmental stages of an owlet moth, 

 Arzatna obliqua (after Claassen). a, a single egg taken from 

 the covered egg cluster, b, and highly magnified; c, the grown 

 larva; d, pupa; e, adult moth. 



