226 PRODUCTIVE FARMING 



of the germs of human diseases. Malaria is spread by mos- 

 quitoes, and in no other way. These malaria organisms 

 are taken into the system of the mosquito with the blood 

 sucked from diseased people. In the mosquito's body certain 



FIG. 124. A. An insect breeding cage, easily made. (Agricultural Education.) 

 B. Moth and pupa cases mounted on cotton under glass. Male cecropia moth 

 above, male polyphemus moth below. (U. S. Office of Experiment Stations). 



changes take place in the life of the organisms which can 

 take place nowhere else. If the mosquitoes were extermi- 

 nated the organisms of malaria could not thrive. When a 

 mosquito attacks a well person some of the germs of malaria 

 are apt to be forced into the blood of the person by the sucking 

 mouth parts of the insect. Thus every new case of malaria 

 is started. 



