THE YELLOW FEVER MOSQUITO 165 



strated. But with yellow fever the carrier is well 

 known to be a common mosquito of the tropics, 

 Stegomyia fasciata, while the infective organism can 

 hardly be said to be demonstrated with certainty. 

 Dr. Seidelin, working at Merida in Yucatan four 

 years ago, found certain bodies in the blood of 

 yellow fever patients. He believes these to be 

 Protozoa responsible for the disease. Other workers 

 have not found these bodies in yellow fever patients 

 on the one hand, or on the other they have found 

 similar bodies in cases of other complaints. More 

 work is necessary before the exact nature of the 

 agent of disease is determined, and some is now in 

 progress in Africa. 



What is the nature of the carrier ? How does it 

 live ? How can it be destroyed ? The answers to 

 these three questions, put into practice, have stamped 

 out yellow fever in many places, and have consider- 

 ably reduced it in others. 



Stegomyia fasciata, also called S. calopus, is a small 

 mosquito about J to i inch long. It appears grey in 

 colour when on the wing, and floats from one place 

 to another like a " bit of fluff." Its thorax possesses 

 two silvery, curved, lateral lines, with two parallel 

 yellow lines between them. The abdomen is dark, 

 with white bands. Its third pair of legs are banded 

 with white, and when the insect alights, it waves 

 these legs up and down. The popular names of the 

 " tiger mosquito " and of the " Scots Grey " have 

 been given to it on account of its markings. The 

 Stegomyia is essentially a house-haunting mosquito, 

 and it is also a water-breeder, utilizing extremely 



