92 



ZOOLOGY. 



food, it nevertheless breathes, and therefore con- 

 tinually uses up body substance. This using up only- 

 takes place to a small extent however, 

 since the animal moves but little. From 

 whence, then, does the pupa get the material 

 to cover the loss of body substance ? In the 

 larval condition the insect takes far more 

 food than it requires for the development 

 of its body, and from this excess it builds 

 up reserve stuffs, which are deposited in the 

 so-called "fat-bodies" of the larva. These reserve 

 materials are re-absorbed during the pupa state, and 

 serve to maintain the breathing. Consequently a 



pupa- that has just 

 been formed moves 

 more than another one 

 just about to become 

 a butterfly. 



The larvae and pupae 

 of the different kinds 

 of insects which under- 

 go a complete meta- 

 morphosis have not the 

 same shape of body. 

 Among the larvae may 

 be distinguished cater- 

 pillars, grubs, and 

 maggots. The caterpillars (Fig. 60) have a clearly 

 marked head with hard covering, three pairs of jointed 

 thoracic legs, and a varying number of unjointed pro- 

 legs. They are usually variegated or green in colour, and 

 are divided into true caterpillars a,nd false caterpillars 

 (Figs. 60, 63, and 64). The first, after the resting 

 pupa stage, become butterflies or moths; the latter 

 sawflies. The true caterpillars have two to five pairs 

 of pro-legs, the false caterpillars six to eight pairs. 

 Reckoning in the thoracic legs, therefore, the true 

 caterpillars have altogether five to eight, the false 



Fig. 6V.— a Hover Fly 

 (Syrphuspyrasii), Fly, 

 maggot, and pupa case. 



