MOSQUITOES AND DISEASE 93 



habitable during the summer. Various preventives have been 

 devised to drive them away. Mixtures of camphor, oil of cit- 

 ronella, and cedar oil when applied to the face and hands will 

 protect one for a few hours; dense smoke will drive them away; 

 and several sorts of gases will expel them from houses, such as 

 burning sulphur, orange peel, or insect powder (pyrethrum). 

 Mosquito bites may be relieved by an application of moist soap, 

 ammonia, alcohol, or glycerin. 



The Yellow Fever Mosquito 



In 1 90 1 the mosquito known to science as Stegomyia calo- 

 pus was proved to be the carrier of yellow fever. This mos- 

 quito lives in tropical and semi-tropical countries, and differs 

 from the ordinary Culex and Anopheles mosquitoes in its habit 

 of biting in the daytime. It will breed in any kind of water 

 and in small amounts, so that the methods of destroying the 

 larvae and pupae are like those employed for the Anopheles 

 mosquito. Outbreaks of yellow fever have occurred in many 

 cities in this country. Philadelphia suffered a severe epidemic 

 in 1793; New Orleans lost 8000 in the epidemic of 1853; in 

 1878 there were 125,000 cases and 12,000 deaths in the Southern 

 States. 



Control in New Orleans. — The last serious outbreak took 

 place in New Orleans in 1905, and its history serves to illustrate 

 the value of the methods of attacking the problems that were 

 then just recently acquired. . The presence of yellow fever in the 

 city was first recognized about the 12th of July, and the plan of 

 campaign adopted was based on the theory that mosquitoes 

 carried the disease. By the 12th of August the increase in the 

 new cases and deaths rendered it practically certain that the 

 disease was as widespread as during the terrible epidemic of 

 1878. There had been up to that time 142 deaths from a total 

 of 913 cases, as against 152 deaths from a total of 519 cases in 

 1878. The work for the rest of the summer was continued with 



