COLEOPTERA (BEETLES). 



The beetles are all grouped under a 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 somewhat 

 worm-like form popularly known as a "grub." This 

 larva, as it is called, bears but the slightest resemblance to 

 its parents. It eats and grows, without essentially altering 

 its appearance until at last it undergoes a molt which re- 

 sults in a sudden change in its appearance. It is no longer 

 worm-like, but looks more like the adult beetle. This 

 stage, which is called the pupa, 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 undergoes no further 

 changes, nor does it increase at all in size. Forms which, 

 like the beetles, pass through these abrupt changes are 

 said to undergo a complete metamorphosis. 



The beetles are divided into two great groups. In the 

 one (Rhynchophora) that part of the head which bears the 



* The elytra of beetles are apparently not the same organs as the 

 anterior wings of grasshoppers or butterflies, but the distinction be- 

 tween the two cannot be made clear here, 



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