64 



ELEMENTAEY AGRICULTUKE 



horn-like and is usually .considered the skeleton of 

 the insect. As it becomes hard it will not stretch; 



and when the insect has 

 grown so large as to en- 

 tirely fill this hard coat, 

 a new or soft coat forms 

 underneath; and the old 

 one is shed or cast off. 

 The casting off of an old 

 coat, or shell, is called 

 moulting. The skin is 

 moulted several times 

 during the life of the 

 insect, and each time it 

 becomes larger. The 

 chief changes in the in- 

 sect's life usually come 

 in the last two moults. 



Courtesy U. S. Dept. of Agriculture 



Fig. 40. Curculio depositing its 

 egg upon a young peach. 



Stages of Development. 



Wasps, bees, butterflies, 

 moths, beetles, flies, and 

 mosquitoes have very re- 

 markable changes in the 

 last moults. Such insects 

 are said to have four 

 stages of life: (1) the o^gg 

 stage, (2) the larva or 

 grub stage, (3) the pupa 

 stage, (4) the adult stage. 

 (Figs. 42 and 43.) 



Courtesy U. S. Dept. of Agriculture 

 Fig. 41. The young grub de- 

 stroying the fruit. 



