a particular species of mosquitoes could not be the sole medium of trans- 

 mission, and that in time to come science will determine other now quite 

 obscure causes. 



Malaria was formerly supposed to be due to bad air, to deadly night 

 air, and to miasmas arising from bad drainage, or from a damp subsoil 

 under houses, or from newly upturned soil. But here it may be well to 

 point out that nearly all these alleged causes of malaria are usually asso- 

 ciated with the existence of pools of stagnant water, or with swamps, 

 which, as entomologists have ascertained, are the very breeding places for 

 the anopheles mosquito. 



If the modern mosquito theory is correct, a person suffering from 

 malarial fever, if bitten by a mosquito, may infect the insect and in this 

 way the latter may by its bite convey the disease germ into the blood of 

 other persons. Hence it is important to protect all malaria patients from 

 being bitten and this applies also to yellow fever patients. Where cases 

 of these two diseases are known to exist, it is imperative that the respec- 

 tive species of mosquitoes be protected from becoming infected, for unless 

 they have become inoculated with the germs of disease, the mosquitoes 

 cannot convey it to persons. 



In the coast regions of tropical and sub-tropical countries, and in some 

 of our southern states, the special mosquito named before, an insect with 

 striped wings, causes by its bite the transmission of yellow fever. 

 According to an article by A. Dastre in the Revue des Deux Mondes of 

 Paris, which appeared in September, 1905, the yellow fever mosquito can 

 live only under conditions of high temperature, and dies when the air is 

 cooler than sixty degrees. The insect bites with energy only when the 

 air temperature is above seventy-five degrees. Hence, in those countries 

 which have extreme heat combined with humidity, the Stegomyia callopus 

 mosquito abounds, and yellow fever is restricted to those localities. 



That yellow fever is conveyed by mosquitoes was first asserted in 1881 

 by Dr. Finlay of Havana. Searching investigations and experiments of a 

 special United States Army Board, in 1890 and later, served to confirm this 

 view. Formerly it was held that filth favored the occurrence of yellow 

 fever, but now it is believed that bad drainage and accumulations of 

 liquid filth are only contributory conditions, because they favor the 

 breeding of the Stegomyia callopus mosquito. 



It is interesting as well as useful to know something of the habits of 

 mosquitoes. These blood-sucking insects breed in stagnant water, in wet 

 marshes or in any pool or permanent water accumulation, such as may 

 be found in badly graded irrigation ditches, or in roof gutters holding 

 water. And they are especially fond of laying eggs in stagnant pools 

 covered on the surface with a green scum. The larvae and pupae which 

 develop from the eggs in a few days, live only in water. Standing water 

 of any kind is therefore the necessary condition for the multiplication of 

 mosquitoes. 



As a rule, the fully developed mosquito flies only for short distances, 

 and the anopheles and inland mosquitoes in particular are said not to travel 

 very far, but the salt water or marsh mosquito is different in this respect, 



8 



