DAHLGREN, THE MALARIA MOSQUITO 43 



far northward and under favorable conditions live, and perhaps breed, 

 is shown by records of yellow fever epidemics in New York and Phila- 

 delphia in the early part of the past century. The success of the sani- 

 tary work done in Cuba under General Wood bears abundant witness 

 to the effectiveness of measures for the extermination of Stegomyia mos- 

 quitoes, and of propei' isolation of yellow fever patients from the insect 

 by the simple means of mosquito netting. 



The Yellow Fever Mosquito is known as a "day mosquito," and was 



formerly considered a species of Culex. The back 



The Yellow Fever 

 of the thorax is marked by silvery stripes, the dark- Mosauito 



brown or black sides of both thorax and abdomen are 

 ornamented with conspicuous white spots, and each segment of the ab- 

 domen bears a white cross-stripe. The knee-spots of the black legs are 

 white, and the tarsal joints are banded with white. These markings 

 make the mosquito quite easy to recognize. 



Insects as Carriers of Disease. 



The whole question of the relation of insects to disease is a subject 

 not only of significance to the medical world and of o-reat interest to the 

 naturalist, affording as it does a striking and most recent instance of the 

 relation of medical science to natural history, but it has also become a 

 matter of general and urgent sanitary importance, and as such demands 

 an enlightened public appreciation. 



Many kinds of insects have been found to be instrumental in the 

 spreading of disease, either by simply conveying disease germs from one 

 place to another, or by actually harboring germs of parasites, which grow 

 and multiply in the body of the insect till they are transferred by its bite 

 to another animal or a human individual. This latter is the case not 

 only in malaria and yellow fever, but also in many of the other most- 

 dreaded diseases of man and beast, in which an insect has been found 

 to serve as the intermediary host for a disease-producing organism. Our 

 first knowledge of an instance of this kind was gained bv the discovery 



in the proboscis of a species of a Culex mosquito bv „ 



-. r • T i- • Filarial disease 



Professor Manson m India (1N<9) ot the minute 



parasitic worm which produces the terrible filarial disease, or elephan- 

 tiasis. 1 Since the time of Manson's discovery new instances of this 



'The filarial! worms find lodgment in the lymphatic vessels and by blocking 

 the natural flow of the lymph at certain points cause enormous enlargement of 

 parts of the body. 



