250 



SYSTEMATIC ZOOLOGY. 



ORDER V. COLEOPTERA. 



The beetles are all grouped under the common head of 

 Coleoptera, the name of which means sheath-wings. Of 

 beetles there are known over a hundred thousand different 

 kinds, but all these agree in the following points: The 

 mouth-parts are fitted for biting; ocelli rarely occur; the 

 pro thorax is large; the anterior wings are converted into 

 thick, horny wing-covers or elytra, beneath which are 

 folded the much larger hinder wings. 



From the egg of the beetle there hatches out a some- 

 what worm-like form popularly known as a 'grub/ This 

 larva (fig. 67 ; b), as it is called, bears but the slightest re- 

 semblance to its parents. It eats and grows, without 

 essentially altering its appearance until at last it under- 

 goes a molt which results in a sudden change in its appear- 

 ance. It is no longer w r orm-like, but looks more like the 

 adult beetle. This stage, the pupa (fig. 67, c), does not 

 eat, but lies quiet in some cavity; after a longer or shorter 

 period of rest it molts again and emerges the perfect 

 beetle, after which, no matter how long it may live, it under- 

 goes no further changes nor does it increase in size. In 



other words the beetles are holometab- 

 olous and, together with the Lepidop- 

 tera, afford the best-known examples of 

 a complete metamorphosis. 



The beetles are divided into two great 

 groups. In the one (Rhynchophora) that 

 part of the head which bears the mouth 

 is prolonged into a snout; in the other 

 there is no such prolongation. These 

 are called the normal Coleoptera. 



The snout beetles (RHYNCHOPHORA) or 

 true weevils are all injurious, since as larvae and adults 



FIG. 74. - - Hazel- 

 nut-weevil (Ba- 

 laninus nasicus). 



