Insecta. 43 



Coleoptera. The beetles are called Coleoptera, mean- 

 ing sheath-winged, from the hard, horny wing covers. 

 The hind wings are membranous, and are usually consid- 

 erably longer than the wing covers. To enable the beetle 

 to protect them there is a joint in the anterior edge of the 

 wing so that it can be folded crosswise as well as length- 

 wise. This is accomplished by moving the abdomen down- 

 ward and backward, then upward and forward to draw the 

 wing under the covers. Some beetles lack true wings and 

 are unable to fly. The mouth parts are fitted for biting. 



All insects have chitin in the skin to stiffen it, but the 

 beetles have this most fully developed, and are the hardest 

 and firmest bodied of insects. This is in keeping with their 

 mode of life, as many of them crawl into crevices, under 

 stones, logs, etc. They are the strongest of insects, and 

 the load they can carry, in proportion to their weight, is 

 marvelous. Beetles have compound eyes, but almost always 

 lack the simple eyes that are present in most insects. 



As the under surface of the abdomen is subject to fre- 

 quent pressure, it needs to be hard and unyielding. How, 

 then, can respiration be effected? It is secured by having 

 the upper surface of the abdomen more soft and flexible ; 

 by the in-and-out movement of this region the air is taken in 

 and sent out through the spiracles, which, except in water 

 beetles, may usually be seen along the abdomen. 



In a former chapter we saw how the dragon fly would 

 have to change if he were to assume the life of a locust. 

 Go a step farther and it will be evident that the beetle, 

 forcing his way into crevices and into narrow places, has 

 acquired the hard, smooth body which he requires to fit 

 him for such a life. 



There is great variety in the habits of beetles ; they live 

 in air and in water; are carnivorous and herbivorous; some 



