PAET I 



THE STRUCTURE AND HABITS OF 

 THE HOUSE-FLY 



CHAPTER I 



INTKODUCTION 



Among the numerous and remarkable advances which have 

 been made in the realm of medical science within the last two 

 decades, none has created so wide a public interest, none has 

 been fraught with consequences affecting so large and wide- 

 spread a proportion of the world's inhabitants, and destined to 

 affect the future welfare and progress of mankind to so great 

 a degi'ee, as the gi'adual discovery of the role which insects 

 play in the dissemination of disease. Malaria, which has had 

 a far-reaching effect on the history of the world and on the 

 immigration of the white man into new regions of the earth, 

 and which in India alone imposes a tax of over a million human 

 lives each year, has been shown to be conveyed by the mosquito. 

 Plague, which in all ages has created terrific devastation, sweeping 

 away millions of lives, transforming populous cities into deserted 

 wildernesses, was found to be transmitted by the flea. The 

 " black sickness," or Kala Azar, which has decimated districts 

 and depopulated areas in the tropical countries where it occurs, 

 has been found to be due to a parasitic organism which can be 

 transmitted by the bed-bug. Sleeping sickness, which numbers 

 its victims by the hundred thousand, depends for its distribu- 

 tion upon the tse-tt ^ fly. Lice have been shown to transmit the 

 causative organism o.^' typhus fever. The common stable-fly has 

 been shown to be a possible disseminator of infantile paralysis 



H. H.-F. , 1 



