CHAPTER XXV 

 INSECTS AND DISEASES 



How do the fly and mosquito differ as regards 

 (a) the harm done, (6) their life history, and (c) the 

 means to be used to control them ? 



It has been proved conclusively within recent years that 

 certain insects are responsible for much sickness and many 

 deaths because they carry the organisms which cause dis- 

 eases. Mosquitoes are known to carry malaria and yellow 

 fever and this is the only method by which these diseases 

 are carried. It is known that house flies are one means of 

 carrying typhoid fever, Asiatic cholera, dysentery, infantile 

 diarrhea, and tuberculosis ; and there is strong evidence that 

 they may carry also smallpox, ophthalmia, and parasitic 

 worms. 



While mosquitoes and flies are the most dangerous in- 

 sects as disease carriers in this country, there are other insects 

 which carry disease. The " spotted " fever of the Rocky 

 Mountain region is carried by a certain tick ; pink eye in 

 the southern states is carried by a small fly; the sleeping 

 sickness in Africa is transmitted by flies ; the bedbug may 

 aid in the dissemination of disease; fleas found on rats are 

 the means of spreading bubonic plague ; and several diseases 

 of domesticated animals are caused by insects. 



i. HARM DONE BY MOSQUITOES 



Mosquitoes and Malaria. Malaria is caused by a micro- 

 scopic animal which lives in the blood. These parasites 



394 



