CHAP. III. THE PUPA STATE. 



23 



Some larvae have the head soft and of no definite shape, 

 such as the larva (Fig. 63) of the Syrphus-fly; it is provided 

 with a pair of hook-like jaws, which are usually curved down- 

 ward. These organs seem to be unfit for masticating food, 

 and are chiefly used to retain the larva in its place, or in hold- 

 ing its prey, and also to assist in moving around. 



The soft, shapeless head occurs only in the 

 larvae of some kinds of Two-winged Flies, such 

 as those of the House-fly (Fig. 64; A repre- 

 sents the young larva, while at B the larva is 

 shown at a more advanced age). 



These larvae are always destitute of legs ? 

 and are commonly called " maggots." 



It is generally in the larva state only that 

 the insect increases in size; the Butterfly or 

 Bee, or any other winged insect, does not 

 increase in size after its wings and other parts 

 have acquired their proper shape and degree 

 of firmness. 



No larva, caterpillar, grub or maggot, is capable of produc- 

 ing eggs or bringing forth young;* these offices are perfomed 

 by the adult insect alone. 



*Some writers claim that there are exceptions to this rule; but these exceptions 

 are of very rare occurrence. 



