CHAPTER XXI. 



Order Coleoptera (Co-le-op'te-ra). 



The Beetles, 



The members of this order have a pair of horny wing-covers, 

 called elytra, which meet in a straight line down the backy and 

 beiteath which there is a single pair of membranous wings. 

 The mouth-parts are formed for biting. The metamorphosis 

 is complete. 



Beetles can be readily distinguished from all other in- 

 sects except earwigs by the possession of horny, veinless 

 wing-covers which meet in a straight Hne down the back 



(Fig. 599); and they differ from ear- 

 wigs in lacking the pincer - like ap- 

 pendages at the tail end of the body 

 characteristic of those insects (see 

 page 103). Beetles also differ from 

 earwigs in having a complete meta- 

 morphosis. 



The name of the order, Coleop- 



^^^' 599. tera, is from two Greek words : coleos, 



a sheath; d^nd pteron, a wing. It refers to the sheath-like 



structure of the elytra (el'y-tra) or wing-covers, which were 



formerly believed to be modified wings. 



These wing-covers apparently occupy the position of 

 the fore wings, and can be moved somewhat as wings are 

 moved. Their structure, however, resembles that of the 

 body-wall rather than that of wings ; and in some beetles 

 (e.g., Dytiscus)Y\xA\mtnts of the fore wings exist beneath the 

 elytra. 



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