Culex 

 mosquito 



\\ 



<s. 



Eggs 



Larvae 



Pupae 



Adults 



Anopheles 

 mosquito 



KINDS OF MOSQUITOES 



The most common mosquito in this country is the Culex, which does not transmit 

 malaria. Malaria is transmitted only by the Anopheles. The two genera are quite 

 distinct at every stage in the life history 



mission consisted of Dr. Walter Reed, Dr. James Carroll, and Dr. Jesse W. 

 Lazear. They were assisted by a Cuban, Aristide Agramonte, who had re- 

 covered from the disease and was therefore immune. 



Two well-screened cottages were used. In one of the two cottages the 

 ventilation was intentionally very poor. In the other, having very good ven- 

 tilation, a mosquito -tight screen separated the two halves. In the first cot- 

 tage three volunteers received clothing and bedding from men who were 

 suffering from yellow fever or uho had died with the disease. Not one be- 

 came infected. 



In the other building eleven volunteers on one side of the screen allowed 

 themselves to be stung by mosquitoes that had drawn blood from yellow- 

 fever patients two weeks earlier: in four days they all came down with the 

 disease. Volunteers on the other side of the screen — breathing "the same 

 air" and living in much the same way, but not stung by mosquitoes — re- 

 mained well. In the course of the experiments Dr. Carroll and Dr. Lazear 

 were also stung and became sick, the latter dying as a result. It has since 

 been found that yellow fever is caused by a virus. 



The mosquito lays her eggs in quiet water. Here the larva and pupa grow 

 and develop. The best means of preventing malaria and yellow fever are 

 therefore (1) ditches to drain off marshy land, (2) cartloads of dirt to fill in 

 low-lying spots, (3) oil on such puddles as cannot be filled or drained, and 

 (4) lids or screens to cover cisterns, tanks or buckets in which water must be 

 kept standing. In addition, it is necessary to make sure that there are no old 



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