256 



ELEMENTS OF AGRICULTURE 



233. Stages in the 

 Life of an Insect. Many 

 insects have four dis- 

 tinct periods in their 

 life. At different stages 

 they look so unlike that 

 one would never sus- 

 pect that they were the 

 same individual. 

 Fig. 133 shows how a common house-fly looks at dif- 

 ferent ages. The first stage is the egg. From this the 

 maggot hatches. This is called the larva stage. When the 

 fly maggot becomes full-grown, it changes to the pupa 



i 2 3 



FIG. 133. Stages in the life of a house-fly: 



3, larva ; 1, pupa; 2, mature fly. (After 

 Howard.) 



FIG 134 Stages of the codling moth: a, the moth or adult insect, slightly 

 enlarged- 6 the egg, greatly enlarged; c, the full-grown larva, slightly enlarged; 

 d the pupa, slightly enlarged; e, the pupa in its cocoon on the inner surface ot a 

 piece of bark, reduced about one-half; /, moth on bark and empty pupa skin from 

 which it emerged, about natural size. (From Simpson.) 



