232 



THE SCIENCE OF LIFE. 



Mandible. 



Maxillary Palp. 



Maxilla. 



Labial Palp. 



Antenna 



Lateral Lobes of 



the Tongue. remaining 



Tongue. 



FIG. 134. Head of a Bee. 



Most Insects undergo metamorphosis, and exhibit 

 four states of existence : egg, larva, pupa, and imago. 



The larva has lit- 

 tle resemblance to 

 its parent, eating 

 and growing rapid- 

 ly. It wraps itself 

 in a cocoon and en- 

 ters the pupa state, 

 ' ig appar- 

 ently dead till new 

 organs are devel- 

 oped, when it emer- 

 ges a perfect winged 

 Insect, or imago. 

 Insects have six legs, each having five parts ; the 

 coxa or hip, the trocliantcr, the tibia or shank, and the 



tarsus. The last 

 is subdivided into 

 joints, generally 

 five, and a pair of 

 claws. Such as can 

 walk on glass, or 

 upside down, as the Fly, have two or three disks (pul- 

 villi) between the claws. It used to be supposed that 

 these disks acted as suckers, but it is now believed that 

 each hair is a minute tube containing a viscid fluid by 

 which the Fly adheres. 



The male of the Great Water-beetle (Dytiscus mar- 

 ginalis] has a peculiar apparatus of suckers, large and 

 small, on his front legs, which may be useful, but, judg- 



FIG. i 35 .-Proboscis of a Dipterous Insect, (Tabanus.) 



