Insect Enemies and Allies 



207 



These germs develop in the mosquito and are thrust 

 into the blood of every person that the mosquito may 

 thereafter bite. 



There are two ways to prevent the spread of malaria : Destroying 

 one by screening to keep the mosquitoes from biting r osqui 

 persons and so carrying the disease; the other by de- 

 stroying the mosquitoes. Draining swamps and pools 

 deprives mosquitoes of their breeding places, and cover- 

 ing all stagnant water with kerosene kills the larvae that 

 may already be in the water. The " wigglers " cannot 

 breathe if there is a film of oil over the water. Mosqui- 

 toes do not fly very far ; consequently, if every one would 

 see to it that no stagnant water was allowed to stand in 

 his neighborhood, or that water that could not be drained 

 was covered with oil, malaria would not be so common. 



Elmer S. Green 



FIG. 161. A rat catcher at work in Colombo. The governments of Ceylon 

 and India carry on a ceaseless campaign of destruction against rats, and they 

 find that it pays. 



