CHAPTER XX. 



Order Siphonaptera (Siph-o-nap'te-ra). 



The Fleas. 



The members of this order are practically wingless, the 

 wings being represented only by minute scaly plates. The 

 mouthparts are formed for sucking. The metamorphosis is 

 complete. 



These tiny tormentors are best known to us in the adult 

 state \ for it is only during this period that they annoy us 

 and our household pets. The larvae and pupae are rarely 

 observed except by students who search for them. 



The name of the order is from two Greek words : siphon, 

 a tube ; and apteros, wingless. It refers to the form of the 

 mouth and to the wingless condition of the insects. 



In our more common fleas the body of the adult is oval 

 and greatly compressed, which allows the insect to glide 

 through the narrow spaces between the hairs of its host. 

 The integument is smooth, quite hard, and naked, except 



that there are many strong spines, 

 which are arranged with great 

 regularity (Fig. 598), and thus af- 

 ford good characters for distin- 

 guishing the different species. 

 The smoothness and firmness of 

 the body makes it easy for the 

 insect to escape when caught be- 



FiG.598.-The Dog-flea and its larva. tween the fingers of man or the 



teeth of lower animals. Doubtless the backward projecting 



490 



