14 



USEFUL BIRDS. 



Most insects emerge from eggs, which ordinarily are de- 

 posited and fixed bj the female parent in positions where 

 . , the young will find suitable food in readiness 

 I ^^^^ ^^^ them when the eggs hatch. Some insects 

 /A bring forth their young alive, but this is an 

 Fig. 5.— Fly and exception to the general rule. The young 

 its larva. inscct that emerges from the egg is called the 

 larva (plural, larvse). Some Iarva3 are provided with short 

 legs or feet, others have none that can be seen ; but all are 

 without wings, and move about mainly by crawling. Their 

 principal occupation is to feed. Some species, such as the 



Fig. 6. — Chestnut beetle or weevil, enlarged, a, larva or grub, enlarged; 

 h, young larva in chestnut, natural size. 



leaf-eating caterpillars, rest during certain parts of the day ; 

 others, like the larvae of flesh-feeding flies, apparently feed 

 constantly. As all eat enormousl}^ and grow rapidly, they 

 are capable, when in great numbers, of doing much harm or 

 good, as the case may be. The larvae of flies are commonly 

 called maggots or slugs, those of beetles are called grubs, 

 and those of butterflies and moths are called caterpillars. 

 Much of the injury 

 done by insect pests 

 is attributable to the 



larVT • a 1 1 h O U o" h ^^S- 7. — caterpillars, the larvie of butterflies. 



some, like certain leaf-eating beetles, are injurious in the per- 

 fect form. During the rapid growth of a larva the skin is 

 shed several times, until full size is reached, when the next 

 transformation is effected, and the larva becomes a pupa or 

 chrysalis. Among the butterflies and moths (Lepidoptera) 

 the insect often spins from within itself a thread, which it 

 weaves into a case or cocoon which encloses it while in the 



