DIPTERA. 



I8 7 



emerges a full-grown fly, complete as to its size and 

 powers. Such flies are oviparous as to their manner of 

 bringing forth their young. (Fig. 76.) This is the meta- 

 morphosis of the majority of the order; but there are flies 

 that bring forth their young in a much more advanced 

 stage; these are called pupiparous flies, as the young in 



n 



FIG. 76. Metamorphosis of an oviparous fly, Phormia regina. 

 B, puparium; C, imago. X 5. (Folsom.) 



A, larva; 



its first stage of life looks like a pupa. And there are still 

 others whose young, when brought forth, are alive and in 

 a stage like the usual larval stage. These flies are called 

 viviparous, or larviparous. 



According to Kellogg, the order may be divided 

 into two grand divisions, (i) those living as parasites on 

 mammals or birds or honey-bees, with the body flattened, 



