308 HOUSEHOLD r\ SECTS 



or they may be carried by flies. One is apt to become 

 infested by sleeping in infested beds in hotels, sleeping- 

 cars, and boarding houses. 



These lice belong to the family of insects known as the 

 Pediculidae, placed by some authors in the order Hemip- 

 tera, but by one author in the separate order Siphunculata. 

 They are characterized, chiefly, by being entirely wingless, 

 with not even a vestige of wings, by leading a parasitic 

 life and by having sucking mouth parts. Among the 

 older zoologists there has been considerable dispute 

 regarding the structure of the mouth parts, whether they 

 were really sucking or biting. In fact, the structure of 

 the sucking tube is not well understood yet. The mouth 

 parts are exceedingly delicate, and always retracted within 

 the head out of sight when not in use. For this reason 

 they are very difficult to study. It is only when the louse 

 is sucking up blood from its host that the rostrum or beak 

 is extended and, of course, buried in the flesh of the animal 

 attacked. 



Schiodte, a Danish naturalist, has given us the most ac- 

 curate description of the rostrum (P. vestimenli) and has 

 given an account of his work in a very pleasing way. He 

 obtained a supply of the lice and confined them in vials for 

 several days without food to sharpen their appetites. At 

 the end of the confinement he transferred one of them to 

 the back of his hand where he could watch its movements 

 with a hand lens. He describes the behavior of the louse 

 as follows : " Scarcely does the abominable little monster 

 feel the heat of the skin before it lays aside its former dis- 

 heartened attitude, and begins to feel at ease, its antennae 

 oscillate for joy, and it stretches all six legs complacently 

 out from the body. But though the pleasure and surprise 



