Twelfth Eeport of the State Entomologist 331 



almost without a consciousness of pain. Thus the rapacious dragon- 

 fly — the hawk of the insect world — would quite as readily eat its own 

 abdomen, as actual experiment has shown, could it conveniently be 

 brought within range of its powerful jaws, as to indulge in its favorite 

 and ordinary mosquito diet. 



Newspaper authority — not always the best in matters of science — 

 has lately (last year) given us another mosquito " boom," in the an- 

 nouncement of the discovery that the Cuban mosquito was about to 

 signalize a great advance in the science of Therapeutics — to serve no 

 less a purpose than an effectual preventive of the fearful disease of yellow 

 fever. The method of protection was simple in the extreme. A bottled 

 mosquito must be applied to the person of a yellow fever patient and 

 permitted to imbibe a little of his blood. Transferred, after a few hours, 

 to the arm of the individual to be protected, the virus received would be 

 conveyed with or through the proboscis, and a successful and complete 

 vaccination against yellow fever will be accomplished. 



The Mosquito as a Filaria Host. 



If the above be only a fanciful conception of some "newspaper man," 

 as it possibly may be, the fact that the mosquito may communicate dis- 

 ease, or aid in its distribution, rests on a scientific basis. Some recent 

 anatomical investigations of a species known as Cnlex 7nosquiio inhabit- 

 ing tropical regions, have shown it as serving a most unexpected purpose 

 in acting as an intermediary host in the life-development of a thread- 

 like worm, — a species of TvArrm. This hiematozoon, bearing the name 

 oi Filaria sanguinis-hominis, is found in its immature or larval stage in the 

 blood of persons afflicted with elephantiasis and some of the allied dis- 

 eases which are endemic over the more thickly populated tropical por- 

 tions of the world. 



Before the filarias can undergo their full development they have to 

 enter some other organism quite different from that occupied by their 

 larvae. The female mosquito above named (and probably other species 

 also) acts as the host in this instance. As she drinks the blood of the 

 diseased person, she imbibes with it the larval filaria. Within her abdo- 

 men they undergo further transformations. Six distinct stages have been 

 recognized within her. As she returns to the water for the deposit of 

 her eggs — with her death occurring soon after oviposiiion, the filariae 

 which she bears in their perfected stage, are consigned to the water. In 

 drinking the water, the parasites are received into the human stomach,, 

 from which they pass to, and enter, the lymphatic vessels, and by their 



