SOME SUGGESTIONS FOR THE STUDY OF INSECTS. 169 



Beetles. 



E.g. Ladybirds, Weevils, Chafers, Ground Beetles, Black 

 Beetles, Turnip Beetles, Water Beetles. Some are best 

 known in their larval stage, e.g. Wireworms, Mealworms. 

 Beetles have two pairs of wings, but the anterior pair 

 is not used in flight. This pair is greatly hardened and 

 thickened and serves as a sheath, covering the hind pair, 

 which are used in flight. 



The jaws are biting organs. 



The larvae are grubs, sometimes soft, in other cases 

 hard. In some the legs are very weak and rudimentary. 

 Aquatic larvae are modified. Fig. 66 3 . 



This Order is known as Coleoptera (sheath winged). 



The insects of the foregoing Orders all undergo a trans- 

 formation or complete metamorphosis in the course of their 

 life-history. There are larval, pupal, and adult stages. 

 But this is not always the case. In some insects there is 

 only a gradual change from the young to the adult con- 

 dition, so that it is customary to speak of direct develop- 

 ment as opposed to metamorphosis. As examples of these 

 we may quote 



Grasshoppers, Crickets, Cockroaches. 



There are two pairs of wings, the fore pair the stronger. 

 The veins upon the fore wings run in straight lines. 



The jaws are biting organs. 



The chief observable difference between young and adult 

 is in size, and in absence of wings in^the former. It is 

 customary to term such a young form a Nymph. It arrives 

 at the adult condition by a series of nioultings ; there is no 

 passive pupal period. 



These insects belong to the Order Orthoptera (straight 

 veins on wings). 



