FLEAS 145 



coat of hair if its body were flat and thin like that of a 

 bedbug. In the second place, many fleas have strong 

 spine-like hairs projecting backward from the posterior 

 edges of the body segments. Undoubtedly, these pro- 

 jecting spines catch around the bases of the hairs and 

 serve to prevent the insect from slipping backward and 

 enable it to push steadily forward. If a flea is caught 

 between the thumb and forefinger, it will gradually work 

 forward in spite of our best efforts and finally escape. 

 Fleas do not have wings and are therefore unable to fly. 

 On the other hand, their legs are very long and well fitted 

 for jumping, especially the hind ones. So that the lack 

 of wings does not seriously handicap them in getting around 

 from room to room or from one animal to another. More- 

 over, each foot is furnished with two claws, which enable 

 them to cling tenaciously to the hairs of their hosts. In 

 some interesting experiments made to determine the 

 jumping ability of the human flea, Mitzmain starved a 

 female five days and then measured her jumps made on a 

 smooth surface of wood. The four jumps recorded 

 measured 10.5, 11, 12, and 13 inches, respectively, an 

 average of llf inches. He also determined that a human 

 flea could jump at least 7| inches in a perpendicular di- 

 rection. 



The eyes of fleas are simple, and in some species, at 

 least, are almost if not quite useless as organs of vision. 



The mouth of a flea is constructed for piercing the flesh 

 and sucking the blood. The mouth parts are composed 

 of several long, slender organs, three of which serve for 

 piercing and all of them together form the sucking tube. 

 It is a very effective apparatus for obtaining blood from 

 its host. The human flea is exceedingly bloodthirsty, 



